Power Line Filter-Pyramidal Horn

Power Line Filter

A device which prevents either radio frequency signals or power line surges from passing along a power cable into equipment.

Power Main Surge Protector

A surge suppressor designed for use at the main power box of a building.

Power Management

Methods used to efficiently direct power to different components of a system. This is particulary important in portable devices which rely on battery power. The life of a battery between charges are extended significantly by powering down components not in use.

Power On

See Power Up.

Power Open

A new operating system which is planned to run on a new super-powerful PC manufactured by a joint IBM-Apple alliance. The idea of the IBM-Apple alliance is make a super-powerful PC that runs virtually every PC operating system imaginable, including MS-DOS, UNIX, Windows , OS/2, Macintosh. The new, all powerful operating system, would be called "Power Open."

Power Over Ethernet

See 802.3af.

Power Product

A cellular radio term . A configurable parameter broadcast by the Mobile Data Base Station (MDBS), defining the desired relationship between received signal strength and transmitted power level at any single point.

Power Regulator

Equipment that regulates the power delivered to a system. Designed to mitigate transients in the commercial electric power source.

Power Rudeness

Ugly behavior enabled by the digital age, such as using beep- ers in theaters, taking cell calls in restaurants and firing employees by email. This definition from Wired Magazine.

Power Seller

A person who make his living buying and selling things on eBay.

Power Spectral Density

PSD. A measurement of the amount of power, measured in Watts, that is applied to the spectrum of carrier frequencies (i.e., the frequency or frequencies that carry the information signal) over a circuit in order to achieve a satisfactory level of signal strength at the receiving end of the circuit. Measured in Watts/Hertz, PSD applies to both electrical circuits and radio circuits. Clearly, every carrier frequency involved in a transmission circuit is at some power level. The PSD level is tuned to the specifics of the circuit, in consideration of the frequency or frequencies involved. In an electrical circuit, the circuit specifics can include the gauge (diameter) of the copper conductor, the number of splices, and the circuit length. Given those specifics, the carrier frequency or frequencies also must be considered . As high-frequency signals attenuate (lose power) more quickly than low-frequency signals, they often are transmitted at a higher power level in order to overcome this phenomenon . However, the combination of the higher frequency signal and the higher power level causes the signal to radiate a stronger electromagnetic field, which can have a decidedly negative impact on adjacent pairs in a multi-pair cable. The adjacent pairs absorb the radiated energy, which takes on the form of electromagnetic interference (EMI), or noise. Therefore, a "PSD mask" must be imposed in order to limit the PSD to acceptable ranges. In ADSL (Asymmetric Digital Subscriber Line), for example, PSD masks are imposed on both the upstream and downstream frequencies. Specifically , ADSL T1.413 standards specify that the upstream passband ( allowable frequency range) of 25-138 kHz, with the associated PSD is -38 dBm/Hz; at frequencies above 181 kHz, the PSD is required to be at least 24 dB below -38 dBm/Hz, i.e., at a level of at least - 62 dBm/Hz (dBm is decibels below 1mW, or milliwatt). See also ADSL, DB, DBM, and Decibel.

Power Splitter

See Power Divider.

Power Supply

Most single line phones are powered by the electricity that comes in over the phone line. That's why they'll work when there's a power outage . Single line phones that have gadgetry associated with them, all ISDN phones and all multi-line phones (like key systems and PBXs) require a supply of power, i.e. electricity, in addition to what they get over the phone line. Most phones and phone systems, like computers, these days are ultimately powered by low voltage direct current (i.e. D.C.). To convert the normal 120 or 240 volts AC power that comes in from your local utility to DC at the various voltages and frequencies needed by the components and circuits of the phone or computer system, you need something called a "power supply." That term may refer to something as simple as a $10 transformer or it may be as complicated and expensive as a $20,000 power supply with an uninterruptible power supply replete with wet cell batteries. Power supplies are usually the least reliable part of modern electronic gadgetry. This is because they take the hits from the lousy power the local utility sends in and also because many manufacturers skimp on the quality of their power supplies . A cheap power supply is not evident immediately. It may take time to break down. Whenever you're having intermittent problems with your phone system or computer, suspect the power supply. And, given a choice, buy the best quality power supply you can. See UPS.

Power Synthesizer

Power synthesizers actually use the incoming utility power as an energy source to create a new sine wave that's free from power disturbances. They can be as much as 99% effective against power disturbances. Types of power synthesizers include magnetic synthesizers (capable of generating a sine wave of the same frequency as the incoming power - 60 Hz), motor generators (which use an electric motor to drive a generator that provides electrical power), and UPSes.

Power Systems

A system that provides a conversion of a primary alternating current power to direct current voltages required by telecom equipment, and may generate emergency power when the primary alternating current source is interrupted .

Power Technology

New technologies to create, distribute and clean electricity. A microturbine is a power technology.

Power Up

The sequence of things you have to do in order to turn a computer or telephone system on. You can't cut corners starting up electronic equipment. It must be done carefully and in the correct order. Always count to ten after turning something off before turning it back on again. See also Power Down.

Power Vendor

One who has a major chunk of a market. Some users believe that a good IS strategy is to buy from a power vendor in the belief that "you can't go wrong buying from AT&T, IBM, Northern Telecom..."fill in the name of your favorite power vendor.

Power, Peak

In a pulsed laser, the maximum power emitted .

Powerline Communications

Sending voice, video, data ” in short telecommunications signals ” over copper wire that normally carry high voltage electricity (110 volts AC and higher) for use in home and businesses for lighting, heating, etc.


Pay per call.


Partial Packet Discard. A technique used in ATM networks for congestion control in support of both Classical IP over ATM and Local Area Network Emulation (LANE). Such data is transmitted in the form of packets and frames , respectively, each of which typically is a subset of a much larger set of data such as a file. In the case of Classical IP over ATM, each data packet can be variable in size , up to a maximum of 65,536 octets (e.g., bytes). As the IP data packet enters the ATM switch on the ingress side of the ATM network, it is stored in a buffer until such time as the ATM switch can segment it into cells, each with a payload of 48 octets ” there can be a great many such cells for each packet ” and act to set up a path and circuit to forward the stream of cells which comprise the original packet. If a given cell is dropped for some reason (e.g., there is not enough buffer space at either the incoming or the outgoing buffer within the switch, the integrity of the original packet is lost. Early implementations of Classical IP over ATM simply forwarded the remainder of the cells associated with that packet. So, the earlier cells made it to the destination device while the later cells didn't. When the cells were reassembled into the packet as they exited the ATM network, the result was an incomplete packet. The higher layer protocols then requested a retransmission of the entire packet. If the ATM network was highly congested , this occurrence was repeated many times, thereby contributing to further congestion. Partial Packet Discard (PPD) involves numbering each cell associated with a segmented packet as it enters the ATM domain through the inbound buffer of the ingress switch. If any cell is dropped, the subsequent cells associated with the packet are dropped, with the exception of the cell indicating the end of the data packet. PPP enhances the performance of the ATM network by dropping those cells, which serve no purpose as the entire packet will be transmitted in either case. PPP is an earlier, and less sophisticated, technique that largely has been replaced by Early Packet Discard (EPD). See also ATM, Classical IP over ATM, EPD, and LANE.


Public Packet Data Network.


Pixels Per Inch. See Resolution.


Pioneer Preference Licensees. A PCS wireless term. Three US companies were awarded licenses before the A and B band auctions began . They all adopted PCS-1900, at least in part.


  1. Pulse Position Modulation. Also known as Pulse Phase Modulation. A form of pulse time modulation in which the position in time of a light pulse is varied; signal amplitude and frequency both remain constant. The typical implementations are known as 4PPM and 16PPM, as a pulse of light is emitted in one of 4 or 16 time slots, respectively. For example, 4PPM is a dibit coding scheme which allows two bits of information to be impressed on a single light pulse, with the exact bit pattern (i.e., 00, 01, 10 or 11) indicated by the specific position in time in which the pulse appears in a synchronized light stream. PPM can be used in both analog and digital transmission systems; it is particularly useful when power requirements must be kept low and when the transmission medium may be pulsed easily. PPM commonly is used in infrared (IR) transmission systems, in both wireless LAN (WLAN) and short-haul networking applications; it also is used in deep-space laser communications systems.

  2. Periodic Pulse Metering.

  3. Private Placement Memorandum. A document that describes a private (i.e. non-public) company's aspirations and attempts to convince some poor unsuspecting soul (like me) to invest their hard-earned money in the company. Sometimes the investment will be turn out good in the long-run. Sometimes it won't. Most times, you have no idea.

  4. Parts Per Million. Also known as Parts of error Per Million, clock slack , drift , skew, slewing rate, and TIE (Time Interval Error). PPM is a measurement of the accuracy of synchronization of a clocking source associated with a switching system or a transmission system. For example, T-1 systems are characterized by clock slack of 50ppm, which translates into 50/1000000 of deviation, or five percent (5%). That means that the accuracy of the clocking source is +/-5% accurate. T-3 systems are characterized by a clock slack of 20ppm, meaning that up there can be a variation of up to 1789 bits in the signal between an incoming and outgoing T-3 facility. Clock slack exceeding this specified ppm causes an unacceptable level of data error.


Processor Port Network, which is the master controller (i.e., CPU) of a proprietary Avaya system.


Point-to-Point Protocol. As defined in RFC 1661, PPP is a Layer 2, or Data Link Layer (DLL), protocol that allows two peer devices (e.g., two host computers, or a host computer and a bridge or router) to transport packets over a simple link. PPP commonly is used to support TCP/IP traffic between an asynchronous PC and an access router for Internet access over a dialup serial link. This generally is the way that you connect across the PSTN from your PC at home to your ISP (Internet Service Provider). PPP is a connection-oriented protocol that encapsulates packet data using a variation on the HDLC (High level Data Link Control) protocol. PPP, which largely has replaced the less robust predecessor SLIP (Serial Line Internet Protocol), supports full-duplex data transmission, both synchronous and asynchronous. PPP includes error detection and data protection features, unlike SLIP. See also HDLC, Link Control Protocol, Multilink PPP, PPPoA, PPPoE, and SLIP.


Point-to-Point Protocol over ATM. A DSL term, defining the use of the PPP protocol over a DSL (Digital Subscriber Line) access circuit running the ATM protocol. At the customer premises, the ATM protocol is embedded in an IAD (Integrated Access Device). At the edge of the network, ATM runs in an ATM-equipped DSLAM (DSL Access Multiplexer). See also ATM, DSL, DSLAM, IAD, PPP, and PPPoE.


Point-to-Point Protocol over Ethernet. Defined in the RFC 2516 from the IETF (Internet Engineering Task Force), PPPoE is a means of connecting from your premises to your Internet Service Provider. Its main advantage is that it eliminates the need for the ISP to manage the allocation of IP addresses. According to www.dslreports.com, PPPoE is a method of encapsulating your data for transmission to a far point. It is very similar to PPP over ATM. In this case though, a DSL modem pumping ATM is internal to the computer, rather than being a short Ethernet cable away. Originally designed for dialup lines, PPPoE is being used by DSL providers to solve the problems they get managing an open DSL network, viz.: IP address shortages, broadcasts not meant for you appearing on your local IP address (because you are on a giant ISP centered virtual net), and other ( mainly ISP-end) difficulties inherent in large bridged networks. See also Ethernet, PPP, and PPPoA.


  1. Pulses Per Second.

  2. Precise Positioning Service. The most accurate dynamic positioning possible with GPS (Global Positioning System), based on the dual frequency P-code.

  3. Packets Per Second. A measurement of the throughput of a packet switch or router, or a packet-based network. For example, the theoretical limit of 10 Mbps Ethernet, when measured in terms of the smallest (i.e., 64-byte) packets, is 14,800 packets per second (PPS). By comparison, Token Ring is 30,000 and FDDI is 170,000 pps.

  4. Path Protection Switched. A ring topology defined by Bellcore TA-496. PPS is really a fancy name for a duplicated SONET signal traveling over diverse (i.e., different) physical routes. When one route of network crashes, the other will take over. This enables it to survive service outages caused by cable cuts, earthquakes, lightning strikes and equipment failures. The PPS ring gives a SONET route a greater degree of survivability than other SONET transmission paths that don't have route diversity. Such SONET rings also are known as "self-healing."


Public Packet Switched Network


Pay Per View.


Public Packet Switched Service. A connection-oriented, packet-switched data communication service that permits users to communicate with data terminals of other customers and on other packet networks.


Point-to-Point Tunneling Protocol, a new protocol that enables virtual private networking ” enabling secure remote access to corporate networks over the Internet. The protocol was first demonstrated at InterOp, Spring 1996. According to the press release from U.S. Robotics and Microsoft which demonstrated the protocol, PPTP will help companies deploy remote access to employees more quickly, using fewer resources, by allowing them to take advantage of existing enterprise network infrastructures such as the Internet for remote access. U.S. Robotics developed the Windows NT PPTP driver, which will be integrated into Microsoft's Windows NT Server 4.0. Under an agreement with Microsoft, U.S. Robotics will license a variety of software components for PPTP to Microsoft. PPTP will be added as a standard feature to Microsoft's Windows NT Server and U.S. Robotics' Total Control NETServer remote access server platform. PPTP streamlines access in NT networking environments, and allows NT network clients to take full advantage of the services provided by Microsoft's RAS (Remote Access Service). For remote access, over analog or ISDN lines, PPTP creates a "tunnel" directly to the appropriate departmental NT Server on a network ” even if there are hundreds of NT Servers. The PPTP specification builds on standards such as PPP and TCP/IP. PPTP 'tunnels' a remote user's PPP packets from the NETServer to a Windows NT server. By terminating the remote user's PPP connection at the NT server, rather than at the remote access hardware, PPTP allows network administrators to standardize security using the existing services and capabilities built into the Windows NT security domain. Using PPTP, network administrators can extend a virtual private network from their Windows NT server throughout the Internet and still retain control of their user passwords and accounts. NT provides its own knowledge of enterprise users, databases, allowed access and network addressing integrated into its RAS capabilities. With PPTP, users accessing their NT-based network will use these services, including DHCP and WINS, for access.


Plastic Quad Flat Pack, a format used in the design of PCMCIA devices. Another format is called TQFP, which stands for Thin Quad Flat Pack.


An ISDN term used internationally to refer to what essentially is an ISDN version of an E-1 trunk from the customer premises to the edge of the ISDN service provider network. PRA, also known as 30B+D, supports 31 channels, in total. The 30 B (Bearer) channels are information- bearing channels; that is to say that each supports the transfer of actual user data. Each of these B channels is a "clear channel" running at 64 Kbps. The D (Data, or Delta) channel is used for all signaling and control purposes (e.g., on-hook and off-hook indication, ringing signals, synchronization, performance monitoring, and error control). The D channel also can be used for end user packet data transfer when not in use for signaling and control, which is its primary function. Many service providers allow multiple PRAs to share a single D channel, since the signaling and control functions are not so bandwidth intensive as to require a full 64 Kbps per PRA. The ITU-T, which sets IDSN standards, specifies that as many as five PRAs can share a single D channel, although a backup D channel is recommended on another PRA circuit. Therefore, the first and second PRAs support 30B+D, and the third-fifth PRAs support 31B+0D. The North American version of PRA is known as PRI (Primary Rate Interface), and supports 23B+D. See also PRI. See also ISDN for much more detail about ISDN, in general.


The technical and installation manuals often used by Bell Operating Companies. A poor use of the word. A better word would be procedure.


The relationships among computing functionality, the users of the functionality, and the users' environment. This includes computing infrastructure issues, performance issues, availability, reliability, security, etc. Similar to Ergonomics.

Prairie Dogging

When someone yells or drops something loudly in a cube farm (an office made up of cubicles), and people's heads pop up over the walls to see what's going on.


See Telephone Man's Prayer.


  1. Pseudo Random Bit Sequence/pattern. A test pattern having the properties of random data (generally 511 or 2047 bits), but generated in such a manner that another circuit, operating independently, can synchronize on the pattern and detect individual transmission bit errors.

  2. A Bluetooth term. Pseudorandom Bit Sequence. pre-paired device A device with which a link key was exchanged, and the link key is stored, before link establishment. See also paired device and un-paired device.


Preemptive rebuttal.

Prepackaged Chapter 11

See Pre-packaged Chapter 11.


PA. A type of SMDS slot defined in support of isochronous traffic such as voice and video. As such traffic is stream oriented and time-sensitive, isochronous data must have regular and reliable access to time slots in order that it might be presented to, travel across, and exit the network without suffering from delay. Otherwise , the presentation of the data through the target device would be most unpleasant (e.g., "herky- jerky video).


A gradual increase in the amplitude of higher frequency signals prior to modulation in order to improve signal-to-noise ratios. This process is often used in frequency modulation (FM) systems to correct for distortion and noise by emphasizing higher frequency audio signals. Pre-emphasis is also sometimes used in certain video circuits.

Pre-emptive Calling

Have you ever had an emergency situation in which you needed to speak with someone, but his or her phone line was busy? Wouldn't it be helpful if your PBX had pre-emptive calling as one of its features? Pre-emptive calling is when a PBX disconnects a low-priority call to connect a high-priority call. When pre-emptive calling is implemented on a private branch exchange (PBX), each phone call is assigned a level of precedence or importance. There are two types of precedence: explicit and implicit. Explicit precedence occurs when a special priority prefix is input before making a call. For example, security managers may be assigned a high priority prefix enabling them to make emergency calls from any phone on the system.

An implicit precedence level can be assigned to an extension and is used automatically when a call is made. A use for implicit precedence might be to assign a high precedence to an emergency phone located in a public area. In either case, the level of precedence is established before the call is connected and is always determined based on the calling party. During the connection process, if the destination is busy, the PBX compares the precedence levels of the established call and the incoming call.

If the incoming call has higher precedence than the established call, the called party may be notified of the higher-precedence call with a display message or voice prompt. If the user does not disconnect from the current call within a set time-out period, the call is dropped automatically, and the call with the higher precedence is then connected to the called party. For cases in which the incoming call does not have a higher precedence, it is handled normally (busy signal, voicemail, auto forwarding, etc.)

Pre-emptive calling is a feature that can provide valuable internal services for enterprise- level PBXs. For instance, a company with remote sites can set up a hotline for each site to the system administrator, so that if something goes wrong the remote site can get immediate help. Other applications include security red phones, special links to business partners , and emergency service notification (police, fire, 911).

Precedence can also be used to seize outgoing or networking trunks if needed in emergency situations. In the case where all of the trunks are in use and a high-precedence call is initiated, one of the calls at a lower precedence level will automatically be disconnected to free the required trunk resource. Thank you Alcatel for this definition.


Imagine a call center with extensive customer records. Perhaps the company is a utility, a phone company or an insurance company. Now imagine that the phone rings. CallerID picks up the customer's name and pops a screen of information on the customer. Meantime, the database system has sent a signal to what's known as "near line" file storage. That near line file storage might be a magneto optical jukebox. It might be a tape file library. The "normal" time to retrieve a record from such systems might range from 30 seconds to two minutes. But if the signal is sent early, the records could be retrieved and loaded into a cache memory, ready if the customer asks a question, for example, about his old bills. This called pre-fetching. See also Pre-Loading.


Or pre-fetching. Documents are manually (by the administrator) retrieved from a jukebox or optical drive on a local area network in anticipation of some special need. Pre-loading may take advantage of the regular cycles of business, such as payroll processing on the 10th and 20th, personnel reviews the first week of each quarter, year-end processing of accounting reports . The network's administrator can take advantage of regular cycles to improve the system's response to users. See also Pre-Fetching.

Pre-packaged Chapter 11

Your company is not doing well. You're about to go broke. You owe everyone too much money. The choice is Chapter 11 in which case you work out a deal with your creditors after you go broke. Or pre-packaged chapter 11 in which you work out a deal with your creditors before you go chapter 11. With pre-pack- aged chapter 11 you know better what the outcome will be. With normal chapter 11, the court appoints trustees you may not like or may have different ideas about how you should restructure your failed company.

Pre-paid Calling Card

A credit card size card which you buy at your local store. Each card comes with information that allows you to use a certain dollar amount of local or long distance phone service. Typically the card will give you an 800 (toll-free number) to call. You call it. You touchtone in the authorization number you find on the back of your calling card and the switch at the other end dials your desired number. The switch measures how long you talk and lets you talk as long as the dollar entitlement on the card ” $5, $10, $20, $50, etc. Pre-paid calling cards are typically expensive for long calls, but cheap for short calls, based on the alternative ” using a credit card with one of the traditional long distance carriers , many of whom apply hefty up-front, per call surcharges. See also Prepaid Calling Card.


See Presubscription.


When you want to order five or more lines from Bell Atlantic, they insist on doing a "pre-survey." This is their mumbo-jumbo way of saying they want to come to your office, and check out the cabling in your building and cabling coming to the building.


  1. Wiring installed before walls are enclosed or finished.

  2. Wiring installed in anticipation of future use or need.


A synchronization mechanism used in Ethernet LANs (Local area Networks), the preamble is a set of eight octets (8-bit values) which precede the Ethernet frame. A very specific bit sequence, the preamble serves to alert each Ethernet-attached device to the fact that a data frame is traveling across the circuit. Once alerted to this fact, the preamble is used by all attached devices to synchronize on the rate of transmission of the data bits across the circuit. See Ethernet.


An electronic circuit which maintains or establishes an audio or video signal at a predetermined signal strength, prior to that signal being amplified for reproduction through a monitor or speaker.


Precedence is Federal government parlance to mean a designation assigned to a phone call by the caller to indicate to communications personnel the relative urgency (therefore the order of handling) of the call and to the called person the order in which the message is to be noted. Autovon phones which have "precedence" have an additional four touchtone buttons. You can find frequencies for those buttons under the definition for DTMF.

Precedence Prosign

An introductory character or set of characters which indicate how a message is to be handled by the receiving unit.

Precise Positioning Service

The most accurate dynamic positioning possible with GPS (Global Positioning System), based on the dual frequency P-code.

Precision Air Conditioning

Precision air conditioning systems are primarily designed for cooling electronic equipment, rather than people. These pre-packaged systems offer excellent reliability and typically have a high ratio of sensible -to-total cooling capacity and a high CFM/ton ratio.


The promise of a paperless office was the most inaccurate prediction. According to the PaperCom Alliance, a nonprofit company that studies the future of paper- based products, electronic communication actually increases paper use in virtually all market sectors. The very upstarts that promised to take advantage of electronic efficiency, e- commerce companies, have consumed massive amounts of paper with their direct mail, catalogs, and print advertising to build brand awareness.

Predictive Coding

Method or source coding using prediction. The prediction error resulting from the difference between the prediction value and actual sample value is transmitted.

Predictive Dialer

A predictive dialer is a machine which makes many outbound calls without people dialing them. It then passes the answered calls to a person. The concept is simple: Machines can make many more calls per hour than a person can. Most calls don't reach people. So it would be a waste of time having a person dial a busy number or an answering machine. I like predictive dialers because they deliver the benefits they promise. And they do it neatly and painlessly. I've never met a predictive dialer user who didn't realize the productivity improvements he was promised and figured on to justify the system. I have only one problem with predictive dialers. Most people use them for collecting money. Dial up the deadbeats. Dun them for money. B-O-R-I-N-G! I'm a mail order junkie. Everyone is. Mail order catalogs have become our escapist reading. I'm dressed in clothes from L.L. Bean, Eddie Bauer, Nordstrom, etc. I'm typing on a computer from PC Connection. My computer is tied into a server. We bought the wire and the server and the network cards by mail order. But I'm an unloved mail order junkie. No one ever calls me. Bean and Bauer know I like "large tall." They know I'm 11N in shoes. They know what I like and what I don't like. I've been buying from them for years . How come they never call me and tell me of their fantastic tall and narrow new products? I'm Platinum on American Airlines. Their most frequent flyer. So why don't they call me and offer me a special " weekend " surprise? Call me on Wednesday. Fill their planes on Friday and Sunday. Don't call me if their planes are full. To my naive brain, predictive dialers are the best sales tool ever invented. They let you sell when you've got something to sell. And not sell when you got nothing to sell. They let you sell "talls" to tall people and narrow shoes to narrowed-footed people. This is not rocket science. One day, some companies will figure there are millions of people (like me) waiting at the end of their phone line waiting for someone to call them and sell them something. That someone, if they're smart, will be using a predictive dialer. See Predictive Dialing.

Predictive Dialing

An automated, computerized way of making many outbound calls without people and then passing the calls to a person as the calls are answered. Here's the story: Imagine a bunch of operators having to call a bunch of people. Those calls may be for collections. They may be for employee callups. They may be for alumnae fund raising. When it's done manually, here's how it works: Before each call operators spend time reviewing paper records or computer terminal screens, selecting the person to be called, finding the phone number, dialing the numbers , listening to rings, listening to phone company intercepts, busy signals and answering machines. Operators also spend time updating the records after each call. Predictive dialing automates this process, with the computer choosing the person to be called and dialing the number and only passing the call to an operator when a real live human being answers. There are are enormous productivity gains made by screening out answering machines, busy signals, network busy signals, non- completed calls, operator intercepts etc. The result is productivity increases of 200% to 300%. According to generally accepted industry lore, a well-run manual dialing center can get its people talking on the phone for 25 minutes an hour. With a predictive dialer you can get them on the phone making sales, collecting money, etc. for 55 minutes an hour. It's a major productivity gain. Predictive dialing needs to be well-managed. Let's imagine a bad predictive dialer (one with a too-simple or incorrect algorithms). It will call too many live people, there won't be an attendant to talk to the person, and the dialer will then hang up on the person it called. However, according to the "Final Amended Telemarketing Sales Rule" (that also established the "Do Not Call" register) effective October 1, 2003, predictive dialers may not abandon more than 3% of calls (measured per-day, per campaign). Also, telemarketers (including people using predictive dialers) have two seconds to connect you to a live person once you pick up the phone and also they must let the phone ring at least four times (15 seconds) before hanging up. True predictive dialing should not be confused with automatic dialing. True predictive dialing has complex mathematical algorithms that consider, in real time, the number of available telephone lines, the number of available operators, the probability of getting no answer, a busy signal, a disconnected number, operator intercept or an answering machine, the time between calls required for maximum operator efficiency, the length of an average conversation and the average length of time the operators need to enter the relevant data. Some predictive dialing systems constantly adjust the dialing rate by monitoring changes in all these factors.

Some people don't like the term "predictive dialing," since they think it's getting "a bad rap" in Washington, DC by being associated with junk phone calls, which it is. As a result some people would prefer to call it Computer Aided Dialing. See also Preview Dialing.

Preemptive Multi-Tasking Operating System

A multi-tasking operating system allows more than one task to be active at the same time. Under Windows 3.x, a task is defined as a single program. For instance, if you have ever had a word processor and a spreadsheet program open at the same time, then you have used Win 3.x multi- tasking. Win 3.x is a cooperative multi-tasking environment. In other words, applications must cooperate for multi-tasking to work. The system cannot preempt the program that has control of the CPU. It is the responsibility of each program to share the CPU. Windows 95 and Windows NT is a preemptive multi-tasking environment. This means the CPU is in charge and can seize control from applications when necessary. This environment reduces the risk of your system freezing up.

Preemptive Operating System

An operating system scheduling technique that allows the operating system to take control of the processor at any instant, regardless of the state of the currently running application. Preemption guarantees better response to the user and higher data throughput. Most operating systems are not preemptive multi- tasking, meaning that task-switching occurs asynchronously and only when an executing task relinquishes control of the processor. See Preemptive, Preemptive Multitasking, Real Time Support.

Preemptive, Real Time Support

When Microsoft released its At Work operating system, it said it had a number of key features, one of which was "pre-emptive, real-time support." Here's Microsoft's description:

  • Pre-emptive, real-time support. Communication devices such as fax machines and phones are distinct from personal computers in that they have critical real-time needs. Consequently, the software in these devices must attend to communication hardware such as modems very frequently, so that pieces of the communication are not lost. To support this need, the operating system was designed to be able to put other processes "on hold" temporarily in order to service the communication hardware before continuing other functions. See At Work and Windows Telephony.

Preference Setting

A set of parameters on software tools, including Web Browsers that allow the user to choose which stuff shows on his screen, which colors he will use to display text, whether a signature file should be attached to his email, etc.

Preferential Roaming

When a mobile user roams, the user's phone will typically choose the network that has the strongest signal when the phone is turned on. Sometimes the default network is different to that which the home network operator would ideally choose; the example, Vodafone D2 would ideally like all its roamers in Italy to use OPI (part of the Vodafone group ). With preferential roaming, a phone's SIM card is programmed to pick up the allied network overriding the strongest signal, thus stopping the paying away of expensive intereconnection fees to other operators. Operators with large international cellular footprints such as Vodafone are keen to exploit this concept to maximize their share of traffic and prevent revenue leakage.

Preferred Call

A local phone company services which lets you forward calls from a bunch of numbers you have pre-selected. The service uses the calling number ID as the basis for choosing which calls to forward.

Preferred Roaming List

A list of SIDs (System IDentification numbers) kept inside a cellphone to permit roaming on other wireless networks. A service provider may set up roaming agreements with other service providers in different geographic regions and the PRL will try to locate one of these service providers' networks first when the home service provider is unavailable. PRLs do change so it's a good idea to ask for a PRL upgrade every 6 months or so if you do a lot of roaming outside your home service area. SIDs are typically five digit numbers which identify the particular cellular carrier from whom you are obtaining service. This number identifies your "home" system. These days, PRL lists are frequently updated via OTA (Over The Air) which makes it much easier for wireless companies to provide the most updated list of roaming partnerships to their users without making them come in to a point of sale.


One or several digits dialed or touchtoned in front of a phone number, usually to indicate something to the phone system. For example, dialing a zero in front of a long distance number in the United States would indicate to the phone company you wanted operator assistance on the call.


Optical fiber source material. Preform is glass rod formed and used as source material for drawing an optical fiber. The glass structure is a magnified version of the fiber to be drawn from it.


Now obsolete term used in certain non-Bell carrier terminal equipments to form up sets of 3 channels for placement into a basic carrier group of 12 channels.


As a noun, it means first in rank or performance. It also is an adjective, as in Premier Issue. See Premiere.


A noun. The first in a series of events or things. The adjective is premier, as in "The premier issue."


A thesis. a proposition supposed or proved as a basis of argument or inference. Often misused to mean the space occupied by a customer or authorized or joint user in a building or buildings on continuous or contiguous property (except railroad rights of way, etc.) not separated by a public road or highway . See Premises.


The space occupied by a customer or authorized or joint user in a building or buildings on continuous or contiguous property (except railroad rights of way, etc.) not separated by a public road or highway.

Premises Distribution System

PDS. There are two meanings for premises distribution system ” a general one and a specific one, specific to Lucent. Here, first, is the general definition. A PDS is the transmission network inside a building or group of buildings that connects various types of voice and data communications devices, switching equipment, and other information management systems to each other, as well as to outside communications networks. It includes cabling and distribution hardware components and facilities between the point where building wiring connects to the outside network lines and back to the voice and data terminals in your office or other user work location. The system consists of all the transmission media and electronics, administration points, connectors, adapters, plugs, and support hardware between the building's side of the network interface and the terminal equipment required to make the system operational.

Here is the specific definition ” A multi-functional distribution system from Lucent to support voice, data, graphics and video communications on premise. PDS includes cables, adapters, electronics, eight pin universal wall jacks and protective devices, all arranged in a logically coherent and economic fashion. It uses fiber optic cable and twisted pair copper wire and is suitable for single building, multi-tenant high rise or campus environment.

Premises Lightwave System

The fiber optic part of the Premises Distribution System (PDS) from Lucent. PDS, which can replace the coaxial cables linking IBM terminals and printers, consists of two fiber optic interface units, one at a controller- end and the optic interface units and one at a terminal-end linked by a fiber optic pair. The fiber optic interface units connect to the terminals through four-pair building wiring and balun adapters. Balun adapters also enable direct connections of the terminals to the cluster controller through building wiring.

Premises Wire

The twisted-pair, quad or other wire installed at the user's location to provide telephone service. Includes both intra-building and inter-building wiring.

Premises Wiring System

The entire wiring system on the user's premises, especially the supporting wiring that connects the communications outlets to the network interface jack.


PowerPC Reference Platform specification. It details the hardware, operating system and software elements necessary to build PowerPC-based systems that meet certain compatibility goals. According to P Magazine, these machines will run 32-bit operating systems and will resemble today's high-end desktop system with lots of memory, CD-ROM drives , stereo audio support, and PCI/PCMCIA expansion buses.

Prepackaged Chapter 11

See Pre-packaged Chapter 11.

Prepaid Phone Cards

With a Prepaid Phone Card, (sometimes called a "Debit phone card") a customer purchases in advance a specific amount of telephone calling time. For example, a typical phone card may offer 30 minutes for about $10.

Prepaid Telephone Card

A prepaid telephone card is a piece of credit-card size plastic entitling the owner to make phone calls. Prepaid telephone cards are sold in many denominations ” typically $1, $5, $10, $20 and $50. Once the owner of the card makes phone calls, the value of the card decreases. The accounting is typically done in a remote switch which the user dials to make his calls. He often dials via an 800 number. Companies sell prepaid telephone calls as a business, often owning the switch and renting the long distance lines. Sometimes companies buy cards from a supplier, print up their names on the cards and give the cards away as promotion. It allows them to reward clients and customers with what one seller of cards calls "a universally valuable commodity ” long distance service." Some people have started collecting prepaid telephone cards the way people collect baseball cards. Surprise, surprise, the value of some telephone cards is increasing. I know someone who has a collection of 30,000 telephone prepaid cards. He tells me he is going to retire on this collection.

A prepaid telephone card doesn't typically have technology on it or embedded into which represents the value of the money remaining on the debit card. Such technology might be an integrated circuit, a magnetic strip, bar codes which can be read by an optical reader. That's a debit card. See Breakage, Calling Card and Prepaid Telephone Card.

Prepaid Wireless

Prepaid Wireless is a system that allows subscribers to pay in advance for wireless service. It is generally used for customers with little or no credit or those with a strict budget.


The industry standard for coin phone operation which requires that the full cost of a call be deposited before a connection is attempted through the Central Office.


The opposite of append. Prepend means added to the front of, whereas append means added to the back of. Prepend is different from precede, which just means comes before, rather than being part of the data frame. See Frame.


Prepended means preceded as part of the same data unit (generic "packet"), whereas appended means succeeded as part of the same data unit. See SMDS.


A device or information handling system which converts raw data into a form more easily processed with standard equipment.




See Presence Management.

Presence Awareness

The New York Times wrote "making a phone call has always been a game of chance. You never know whether the person you are calling is available. You just punch in the numbers and hope to get lucky. Imagine being able to learn without dialing a single digit whether another person's phone is in use, or in the case of a cellphone, whether it is even turned on. Now imagine being able to do the same thing with any wired or wireless device of the future ” whether it is in the car, in an airplane or at the gym. Not only could you learn whether a person is available for a chat, but you could also deduce what that person might be doing at that exact moment, all without exchanging a word. That is the idea behind a programming concept called presence awareness, which is based on the realization that appliances on a network can automatically be detected by other devices."

Presence Management

Presence management is the ability to tell your phone system via a web interface, application running on your PC, or phone interface whether I am at my desk, traveling, in meetings, etc and have the phone system find me and my connect calls. It combines one number dialing and multiple outbound calls to help connect people to me, if I want.

Presentation Address

According to the book, "Internetwork Mobility," by Mark Taylor, William Waung and Mohsen Banan, the presentation address is the network name of an Application Entity within a Data Service. The Presentation Address takes the form of: optional Presentation Selector (SSAP-Selector + Session Selector (TSAP-Selector) + Transport Selector (NSAP-Selector) + a required NET. Presentation Addresses are stored in the Directory Service. Application Entity Titles are used to retrieve the Presentation Address from the Directory Service.

Presentation Indicator

PI. An ISDN term. See PI.

Presentation Layer

The sixth layer of the OSI model of data communications. It controls the formats of screens and files. Control codes, special graphics and character sets work in this layer. See OSI Standard.

Presentation Manager

Presentation Manager is a look and feel specification and kernel-based toolkit development environment. It was developed for IBM by Microsoft with input from IBM. Presentation Manager is the standard graphical user interface and toolkit for the OS/2 operating system, which is a multi tasking operating system for personal computers. The screens are similar to those of Microsoft Windows.

Presentation Status

For a particular call, an item that indicates if a calling identity item may be presented to the called party. If the presentation status is "public" presentation is allowed. If it is anonymous", presentation is restricted. Presentation status has to do with the presentation or not or calling line identification numbers.


The "programming" of radio station frequencies on a tuner or receiver or musical selections on a tape, for instant recall at the push of a button.

Preset Call Forwarding

Incoming calls will be re-routed to a pre-determined secondary number.


Telephone circuits are two way. Some circuits, such as mobile dispatch services for taxis, etc., are one-way. They use a microphone or handset with a button you must press-to-talk and release to listen. You can also buy a normal telephone hand- set with a press-to-talk button. Such a handset is useful in noisy places.

Pressure Cable

Telephone cable equipped with air-pressure equipment so the phone company can determine when there's a problem with the line. When a cable is cut, the pressure drops and the company is notified of the problem. Nitrogen is often used instead of air because it's noncorrosive. Nitrogen also prevents water entering the cable when there's a break.

Pressure System

An intricate system of hollow tubes, copper cables and air compressors designed to force compressed air into the sheaths of some copper cables. The intent of the system is to prevent moisture from entering the cable by the escape of the compressed air through any cracks or holes which develop in the cable sheath. See also Pressurization.


Pumping inert gas into a heavy casing in which a couple of thick cables will be joined. The pressure is usually maintained at a few pounds above the surrounding atmospheric pressure. The idea is that the higher pressure inside keeps moisture out of the splice and thus improves the quality of phone service.


A videotex system used only in Britain.

Prestel Terminal Emulation

Prestel is a character-based graphics emulation for communicating with the Viewdata service, particularly popular in the United Kingdom.


A local Bell or local independent operating telephone company service that encourages each subscriber to select one long distance carrier he may use without having to dial a multiple digit access code. If you pre-subscribe to MCI in America, you will simply reach MCI by dialing "1" plus the 10-digit long distance number. AT&T's code is 10-10-288 (as in 1-0-ATT). Sprint's is 10-10-333.


During the communist era in Russia, people, lamenting on how bad things were, used to quip, "We pretend to work and they pretend to pay us." My daughter claimed on her graduation and after thousands of dollars of school fees, she would soon pretend to work and soon pretend to get paid. I'm praying.


A central office malfunction that causes a phone to ring only once, and then stop, as if it had been answered. IT can be very confusing and difficult to get repaired, because most telco repair people have never heard of the problem and will insist your phone is at fault. Often fixed by replacing a faulty heat coil.

Pretty Good Privacy

A powerful encryption scheme. See PGP for a full description.


An office automation UNIX software package which combines functions usually available only in individual programs, such as spreadsheet, a word processor, a database management system, communication capabilities and more.

Preventive Maintenance

The periodic inspection, cleaning, adjusting and repair to eliminate problems before they affect service. Usually ignored.

Preview Dialing

Preview dialing is a term used to describe an automatic dialer. Preview dialing is also called "screen dialing" or "cursor dialing." Typically the prospect's account information and/or phone number appears on the screen BEFORE the call is made. Thus the agent can "preview" the number, the screen, the customer. If the agent wants to make the call, the agent hits a key, such as "Enter" and the computer dials the number. In some preview dialing equipments, the agent must hit a key if he/she DOESN'T want the number dialed. Contrast preview dialing with Predictive Dialing where the computer makes all the dialing decisions and presents the calls to the agent only after they are connected. Predictive dialing is a lot faster than preview dialing. See Predictive Dialing.


  1. Wiring installed before walls are enclosed or finished.

  2. Wiring installed in anticipation of future use or need.


Primary Rate Interface is an ISDN term used internationally to mean refer to what essentially is an ISDN version of a T-1 trunk from the customer premises to the edge of the ISDN service provider network. Also known as 23B+D, PRI supports 24 channels, in total. The 23 B (Bearer) channels are information-bearing channels; that is to say that each supports the transfer of actual user data. Each of these B channels is a "clear channel" running at 64 Kbps. The D (Data, or Delta) channel, which also runs at 64 Kbps, is used for all signaling and control purposes (e.g., on-hook and off-hook indication, ringing signals, synchronization, performance monitoring, and error control). The D channel also can be used for end user packet data transfer when not in use for its primary function of signaling and control. Many service providers allow multiple PRIs to share a single D channel, since the signaling and control functions are not so bandwidth intensive as to require a full 64 Kbps per PRI. The ITU-T, which sets IDSN standards, specifies that as many as five PRIs can share a single D channel, although a backup D channel is recommended on another PRI circuit. Therefore, the first and second PRIs each support 23B+D, and the third-fifth PRIs each support 24B+0D. The international version of PRI is known as PRA (Primary Rate Access), and supports 30B+D. See also PRA. See also ISDN for much more detail about ISDN, in general.


A fax signal. PRocedure Interrupt-End of Page.


A fax signal. PRocedure Interrupt-MultiPage Signal.

Price Cap

The phone industry has always been regulated on the basis of the profits it earns compared to the investment it had. That was called Rate of Return Regulation. How you figure profits ” since you also have to figure what are allowable expenses ” has been the subject of on-going debate for over 100 years. The latest idea in regulation is to replace the rate of return regulation with something called "Price caps" which allow the price of phone company services to rise by x% at maximum ” the so-called price cap.

In November, 2002, UBS Warburg wrote this about Price Cap Regulation: "The regulatory framework wherein regulators set limits on prices operators can charge for qualified telecom services. Price caps are set based on a formula that is typically influenced by some inflation factor (e.g., CPI plus 200 basis points). This regulation provides carriers an operating efficiency incentive in that it does not explicitly limit a company's level of profits. As a result, a carrier that provides service for less than its expected cost benefits. Price cap carriers take on greater risk for a greater potential reward. Price cap regulation typically exists in urban and suburban jurisdictions and markets that are open to competition. The FCC mandated this regulatory regime at the federal level for the RBOCs and GTE in 1991. RLECs such as Citizens, Iowa Network Services, and Valor Telephone are also price cap at the federal level."

Price Earnings Ratio

P/E Ratio. This ratio theoretically measures the value of a stock by dividing its current price on the stock market by its earnings per share over the last twelve months. When a stock's P/E ratio is high,it is considered by investors as pricey or overvalued. Stocks with low P/Es are considered good value. When stocks rose strongly (for example, in the first quarter of 2000), P/E ratios got very high. And investors sought ways to justify the high ratios. They started, for example, to figure P/E ratios on the basis of next year's earnings (which presumably, being higher, would bring the P/E ratio more down to earth). In his studies of blue chip stocks, the publisher of Investors Business Daily, William J. O'Neil, found the higher the P/E, the better the stock and the better its performance. The average P/E of the best winners over the last fifteen years at the initial buy point prior to their huge price increases was 31 times earnings. These P/Es went on to expand more than 100% to over 70 times earnings as the stocks significantly increased in price. P/Es are misunderstood and misused by many investors, according to Mr. O'Neil.

Primary Agent Group

An automatic call distributor term: Primary agent group for which the inbound calls are intended. Intraflow goes to secondary and tertiary groups if the primary group does not have an agent available after the time or after overflow parameters are exceeded. Different ACD systems label this process differently.

Primary Alias

A term used in the Sun Solaris Teleservices platform. See Provider.

Primary Area

A customer's local telephone calling area.

Primary Bill Version

A Verizon definition. This version of the bill is delivered electronically or by a cartridge tape that contains the monthly CLEC or Reseller bill in Bill Data Tape (BDT) formatted records.

Primary Buffer

A part of a computer's memory where fast incoming or outgoing data is kept until the computer has a chance to process it.

Primary Carrier

Customer's selection of a long distance carrier (IC) to automatically carry his or her traffic in equal access areas.

Primary Center

A control center connecting toll centers ” a Class 3 Central Office. It can also serve as a toll center for its local end offices.

Primary Colors

In light (and in monitors , which produce light) the primary colors are the basic colors - red, green and blue - that can be added together to create any other color .

Primary Domain Controller

PDC. For a Windows NT Server domain, the computer that authenticates domain logons and maintains the security policy and the master database for a domain. See Domain.

Primary Group

A group of basic signals which are combined by multiplexing. The lowest level of the multiplexing hierarchy.

Primary High-Usage Trunk Group

A high-usage trunk group that is offered first-route traffic only.

Primary Insulation

The first layer of non-conductive material applied over a conductor to act as electrical insulation.

Primary Interexchange Carrier

PIC. A Primary Interexchange Carrier is the long distance company to which traffic from a given location is automatically routed when dialing 1+ in equal access areas. The PIC is identified PIC Code (PICC) which is assigned by the local telephone company to the telephone numbers of all the subscribers to that carrier to ensure the calls are routed over the correct network. When a subscriber switches long distance carriers, it often is referred to as a PIC change. A LPIC is an IntraLATA Primary Interexchange Carrier, which may be different from the InterLATA PIC.

Primary InterLATA Carrier

The IC designated by a customer to provide interLATA service automatically without requiring the customer to dial an access code for that carrier. See Presubscription. Same as a Primary Interexchange Carrier.

Primary Link

The active LAN connection. When it fails the LAN is switched to the Backup link.

Primary Partition

A portion of a physical disk that can be marked for use by an operating system. Under MS-DOS, there can be up to four primary partitions (or up to three, if there is an extended partition) per physical disk. A primary partition cannot be sub- partitioned.

Primary Rate Access

See PRA.

Primary Rate Interface

The ISDN equivalent of a T-1 circuit. The Primary Rate Interface (that which is delivered to the customer's premises) provides 23B+D (in North America) or 30B+D (in Europe) running at 1.544 megabits per second and 2.048 megabits per second, respectively. There is another ISDN interface. It's called the Basic Rate Interface. It delivers 2B+D over either one or two pairs. In ISDN, the "B" stands for Bearer, which is 64,000 bits per second, which can carry PCM-digitized voice or data. See ISDN for a much better explanation.

Primary Resource

An SCSA definition. The main resource around which a Group is constructed . Typically, the primary resource will be an interface to the telephone network, but it may also be a switch port.

Primary Routing Point

The switch designated as the channel point for a long haul telephone call.

Primary Server

The SFT III Novell NetWare server that has been operating longer than its partner and is currently servicing the attached workstations. The primary server is the SFT III server that network workstations "see," and the one to which they send requests for network services. Routers on the internetwork see only the primary server and send routing packets to it. The primary server's IOEngine determines the order and type of events that are sent to the MSEngine. Only the primary server sends reply packets to network workstations. The secondary server is the SFT III NetWare server that is activated after the primary server. Either server may function as primary or secondary, depending on the state of the system. You cannot permanently designate which server is primary or secondary. System failure determines each server's role, that is, when the primary server fails, the secondary server becomes the new primary server. When the failed server is restored, it becomes the new secondary server.

Primary Station

A network node that controls the flow of information on a communications link. Also, the station that, for some period of time, has control of information flow on a communications link (in this case primary status is temporary).

Primary Storage

The main internal storage.

Primary Wire Center

A switching center in the AT&T/Bell system hierarchy of exchange classes. The primary center is a Class 3 exchange. It is used to connect toll offices and less frequently to connect a toll center with a local end office. Primary centers are capable of connecting toll centers through sectional centers and then to local end offices to establish communication connections when simple routing possibilities are busy.

Prime Focus Parabolic Antenna

There are two types of satellite antennas ” a prime focus parabolic antenna and an offset parabolic antenna. A "normal" satellite antenna is a pure parabola. It's been around forever. A newer antenna, called the offset antenna is taller than it is wide. According to the manufacturers, the offset antenna design makes for more efficient use of the antenna surface than a traditional prime focus parabolic antenna. What that means is that it captures more of the satellite signal hitting the antenna. Offset antennas are more expensive than the "normal" parabolic satellite antennas, which are called "prime focus parabolic antennas." They are more expensive because they cost more to make since they typically must be made out of one sheet of metal. Offset antennas are harder to carry around, since you can't make them out of several foldover sheets of metal.

Prime Line

A key system feature. You can program your phone set to automatically select a certain phone line whenever your lift the receiver or press the Handsfree/Mute button. The line that appears is called the Prime Line.

Prime Line Preference

When you pick up the handset on your key system or hybrid key, you are automatically connected to your preferred line (central office or intercom), rather than having to punch down an extra line button. Some phone systems tout this as a feature. Some have it set up where you simply leave one of the line buttons depressed and it doesn't pop up when you put your handset back into its cradle. Most 1A2 phone systems have this feature. Not all electronic phone systems do. Walker breaks the features into Prime Line Outgoing and Prime Line Incoming, and allows you to program the phones separately.


An abstract, implementation independent, interaction between a layer service user and a layer service provider. See Primitives.


Abstract representations of interactions across the service access points indicating information is passed between the service user and service provider. There are four types of primitives in the OSI Reference Model ” request, indication, response and confirm.


First or highest in importance. An owner or part-owner of a business. A person who authorizes another, as an agent, to represent him. Often confused with principle, not that a principal necessarily has any principles. See Principle.


A general or fundamental truth on which others are based. A rule of conduct. Often confused with principal. See Principal.

Principle Headend

According to the FCC's definition, the principal headend of a cable television system is: If the system has one headend, that headend is the "Principal Headend" and if the system has two or more headends, the operator may designate the "Principal Headend". However, once designated, it cannot be changed except for "good cause". The location of the Principal Headend is a factor in determining the must-carry status of certain broadcast stations .

Principles of Operation

POP is a manual for IBM Mainframe Systems such as S/360, S/370, S/390, etc. which describes how each of the assembler instructions operates. It is considered the Systems Programmer's "bible", commonly referred to as a "POP".

Print Control Character

A coded control character used to instruct the receiving unit on how a message is to be formatted in hard copy. Print control characters include carriage returns, back spaces, line feeds, tabs, etc.

Print Server

A networked computer, usually consisting of fixed-disk storage and a CPU, that controls one or more printers that can be shared by users.

Print Spooler

An application that manages print requests or jobs so that one job can be processed while other jobs are placed in a queue until the printer has finished with previous jobs. See Print Spooling.

Print Spooling

A technique used to schedule printing tasks to one printer and to free up computer time from the slow task of feeding a slow printer (Any printer is slow compared to the speed of a computer). A small program or program/machine called the spooler does the scheduling. A user loads the print task to the spooler and when the print task's turn comes, the job is printed. Print spooling is handled several ways: You can allocate part of the computer's main memory to become a print spooler. You can allocate part of the company's disk memory to become a print spooler. You can get an external device called a print spooler. It will have all the storage space and software necessary. There are two primary advantages to Print Spooling:

  1. You can use the spooler to save your and your computer's time. Dump the report to a print spooler at thousands of bits per second. Get on with something else on the computer.

  2. You can use a print spooler to schedule several users' printing requests. This is particularly good in multi-user environments ” for example, where the printer is a laser printer (and therefore expensive) and is attached to a LAN (Local Area Network).

Printed Circuit Board

PCB. Flat material (fiberglass/ epoxy ) on which electronic components are mounted. A PCB also provides electrical pathways called traces, that connect components. Printed circuit boards are what PBXs and computers are made of these days. Be careful when you're replacing PCBs. They're usually very sensitive to static electricity. Handle them only when you're attached to a static electricity strap that is properly grounded. Lay them down only on a surface you're sure is static electricity free. And don't touch the components on PCBs whatever you do.

Printed Wire Assembly

A printed wire assembly is another name for a printed circuit board (PCB) or printed wiring board (PWB) with all the components stuffed into the board.


A device which takes computer information and prints it on paper.

Printer Control Language


Printer Driver

A program that controls how your computer and printer interact. A printer driver file supplies information such as the printing interface, description of fonts, and features of the installed printer.

Printer Emulation

A fax term for mimicking a printer-generated document. This way, the outgoing fax will look as if it has come from the printer attached to the computer. This can include full formatting, as well as letterhead, signature and graphic images.

Printer Font

A font stored in your printer's memory, or soft fonts that are sent to your printer before a document is printed.

Printer Server

A computer and/or program providing LAN (Local Area Network) users with access to a centralized printer. A person using the LAN will send a message to the printer server computer. This computer will then assign it a piece of memory or disk space to store its file while it waits to be printed. With a printer server, users can send to the printer any time. Their print jobs are usually handled in the order they are received. But "big bosses" can be given priority and can be bumped to the top of the queue. Print servers allow fewer printers to satisfy more users. Print servers are also especially useful for expensive, laser or high speed printers because they (the print servers) spread the cost of these expensive machines over many users, making them more affordable. See Print Spooling.

Printer, Wire

A matrix printer which prints using a set of wire hammers which strike the page through a carbon ribbon to generate the matrix characters.

Prior Art

Let's say you file a patent application for your latest, greatest invention. You get issued the patent and you now believe you're protected and will soon be rich and famous. Meantime, someone steals your idea and starts making a product that looks remarkably what you thought of. So you sue them to stop or at least pay you a royalty. In turn, they argue in court that your patent is not valid as a result of "prior art." What that means that a previous publication or patent is deemed to provide essential details of aspects of your invention and therefore your patent is invalid and you can go pound sand. There seems to be an unlimited demand for early editions of my dictionary. Lawyers want to prove that your patent is valid (because of prior art) and therefore their client can continue ripping you off. See Patent.


The process of assigning different values to network users, such that a user with higher priority will be offered access or service before a user with lower priority. Increasingly available as an added option with network operation. Any procedure where different levels of precedence exist.

Prioritization Parameters

The hierarchical rules which a network device, such as a router, applies to incoming traffic to determine which traffic should be handled first, next, and so on.


A ranking given to a task which determines when it will be processed.

Priority Access Methods

When there's an emergency, say a flood or volcano explosion or the September 11, 2001 attack on the World Tr4ade Center, various government authorities need to get access to communications facilities, like cell phone bandwidth. Unfortunately, when a disaster happens everybody and their uncle jumps onto their cell phones and everybody promptly gets fast busy signals ” including the important emergency people. So the concept of priority access methods is to figure a way of returning a fast busy to normal cell phones, while allowing the important people to get through, i.e. to get priority access.

Priority Bumping

The process during a link, trunk or facility failure where lower priority user access to network services is interrupted in order to offer those services or bandwidth to a pre designated higher priority user.

Priority Call

  1. Emergency calls to the attendant bypass the normal queue and alert the attendant with some special signal.

  2. The name of a Bell Atlantic service. While all callers are important, some are more critical to your business. So give your high-priority callers a ring of their own with Priority Call. Simply use your phone to program up to six callers ' numbers. When any of these people call, you'll know right away because you'll hear a different ring. If you have Call Waiting, you'll hear a Priority "beep" when you're on the phone. This way, you'll only have to interrupt your work to take priority calls.

  3. This PBX feature allows an urgent intercom voice call to be made when the called telephone is busy or has Do Not Disturb activated. Priority Call should not be made available to everyone, and should be selectively programmed.

Priority Indicator

A character or group of characters which determine the position in queue of the message in relation to the urgency of other messages. Priority indicators control the order in which messages are to be delivered.

Priority Ringing

A name for a Pacific Bell (and possibly other local telephone companies') service which alerts you to have calls from selected numbers ring at another number.

Priority Transport

The capability of a network for certain classes of traffic to have priority over others and thus have lower delay or otherwise better performance.

Priority Trunk Queuing

Through user- chosen trunk access level, this PBX feature places any caller with this or higher level in the class of service assignment ahead of callers waiting for the same trunk group (or Agent Group in the case of incoming ACD calls).


Privacy usually means that once a caller "seizes" a line, no other user can access that same line even though it appears on his/her key set. Privacy can be automatic or selected for each call.

Privacy And Privacy Release

All other extensions of a line are unable to enter a conversation in progress unless the initiating telephone releases the feature.

Privacy Compromise

A network security term. A scenario in which a malicious user is able to gain access to personal or confidential information about another user.

Privacy Enhanced Mail

PEM. An Internet electronic mail capability which provides confidentially and message integrity using various encryption methods.

Privacy Lockout

Privacy automatically splits the connection whenever an attendant would otherwise be included on the call, i.e. the attendant can't listen in to a call she's just extended to someone. A tone warning is generated when the attendant bridges into a conversation in progress.

Privacy Override

Activation of a special pushbutton allows the phone user to access a given busy line, even though the automatic exclusion facility is being used by the station on that line. This privilege of Privacy Override is usually only given to Big Bosses.

Private ATM Address

A twenty-byte address used to identify an ATM connection termination point.

Private Automatic Branch Exchange

PABX. A private telephone switch for a business or an organization in which people have to dial "9" to access a local line. In the old days, private branch exchanges were manual, meaning that operators/attendants were needed to manually place calls. Then the systems improved and you were able to dial the outside world from your extension without the help (or hindrance?) of an operator. Thus they became known as private automatic branch exchanges. But then all PBXs became Automatic. So these days, PABXs are all called PBXs, except in some countries outside North America, where they're still called PABXs. See also the next definition and PBX.

Private Branch Exchange

PBX. Term used now interchangeably with PABX. PBX is a private telephone switching system, usually located on a customer's premises with an attendant console. It is connected to a common group of lines from one or more central offices to provide service to a number of individual phones, such as in a hotel, business or government office. For the biggest definition, see PBX. See also PABX.

Private Carrier

An entity licensed in private services and authorized to provide communications service to others for money.

Private Dial-In Ports

A packet network term. For customers who have many calls, the packet network operator provides dedicated, unpublished phone numbers. The idea is to give the preferred user better service.

Private Domain Name

A standard attribute of an O/R (Originator/Recipient) Address that identifies a PRMD (Private Management Domain) generally relative to an ADMD (Administrative management Domain). An X.400 term.

Private Equity Fund

A bunch of people and organizations pool their money and hire a manager or team of managers, who invest the money, buying various private businesses and listed equities. The managers typically get paid a percentage of the monies managed and perhaps a reward should certain profit goals be reached. Private equity funds typically have a life of five to seven years at which point the investments are typically sold and the monies distributed to the owners , i.e. the people and organizations who put their money in the first place. Hopefully, there's a profit in the long-term. See also Hedge Fund and Mutual Fund.

Private Exchange

PX. A telephone switch serving a particular organization and having no means of connection with a public exchange. In other words, a phone system just for intercom calls.

Private Eye

Around 1925, the Pinkerton Detective Agency adopted "We Never Sleep" as its motto. To symbolize this, the motto was shown over the picture of an open, ever-wakeful eye. The popularization of this emblem led to private detectives being called "private eyes."

Private Facility Trunk

A telephone company AIN term. A transmission facility that carries non-public switched telephone network (PST) traffic. An example of a private facility trunk is an access arrangement to a switch supporting PBXs, including the switched end of a Foreign Exchange (FX) and an Off Network Access Line (ONAL).

Private Internet eXchange

PIX. It's a Cisco term for a family of their remote access routers with firewall capabilities.

Private Key

In asymmetric key cryptography, the private key is the key that must not be divulged to others. Private key encryption requires that the decrypting key be kept secret. Also known as single-key and secret-key. See Public Key Encryption and Encryption for more detail.

Private Leased Circuit

A leased communications circuit, available 24 hours a day, 7 days a week, that connects a company's premises with a remote site.

Private Line

  1. A direct circuit or channel specifically dedicated to the use of an end user organization for the purpose of directly connecting two or more sites in a multisite enterprise. A private line that connects two points together is known as point-to-point; a private line that connects one point to multiple points is known as point-to-multipoint. Private lines are leased from one or more carriers, which may be local or interexchange in nature. Private lines provide connectivity on a non-switched basis. As they bypass the network switches, private lines use the various switching centers (e.g., Central Offices, or COs) only as wire centers for the interconnection of circuits. Thereby, private lines provide full-time and immediate availability, eliminating dialup delays and avoiding any potential for congestion in the core of the carrier networks.

    Private lines offer highly available connectivity, as they are dedicated to the use of a single organization, which may run any type or combination of traffic types over them. As private lines are priced based on distance and bandwidth, with no usage-sensitive cost element, they can be used constantly and at maximum capacity at the same cost as if they were never used at all. Therefore, they offer a highly cost-effective to usage-sensitive, switched services in environments where communications between sites is frequent and intense . Originally, private lines were, in fact, dedicated circuits which literally could be physically traced through the network. They also were known as "nailed-up circuits," as telephone company technicians hung the physically distinct circuits on nails driven into the walls of the central offices. Contemporary private lines actually involve dedicated channel capacity provided through the core of the carrier networks over high-capacity, multi-channel transmission facilities. The access portions (i.e., the local loop portions) of the private line are, of course, dedicated and physically distinct circuits.

    Private lines are agnostic with respect to the form of the data, and the nature of the application. They can support voice, data, video, facsimile , or multimedia communications. They can run at rates of T-1, NxT-1, T-3, OC-3, or any other technically feasible speed. They can support any communications protocol, or combination of protocols, including TCP/IP, Frame Relay, or ATM. See also Private Network.

  2. An outside telephone line, with a separate telephone number, which is separate from the PBX. The line is a standard business line which goes around the PBX. It connects the user directly with the LEC central office, rather than going through the PBX. Private line connections are considered to be very "private" by virtue of the fact that it is not possible for a third party (e.g., technician or console attendant) to listen to conversations without placing a physical tap on the circuit. Additionally, private lines are not subject to congestion in the PBX. As private lines also are not susceptible to catastrophic PBX failure, they often are used to provide fail-safe communications to key individuals with mission-critical responsibilities in data centers, network operations centers, and the like.

Private Line Service

An outside telephone number separate from the PBX, can be set up to appear on one of the buttons of a key telephone. Also called an Auxiliary Line. See also Private Line.

Private Management Domain

PRMD. An X.400 electronic mail term: A private domain to which MTAs (Message Transfer Agents ) send mail. PRMDs are connected to ADMDs (Administrative Management Domains) for message routing over wide area links. Under X.400 addressing, the PRMD represents a private electronic messaging system that may be connected to a Administrative Management Domain. The PRMD is usually a corporate or government agency email system connected to an ADMD.

Private Message

A message designation which prevents that message from being given to another mailbox.

Private Network

  1. A network built and owned by an end user organization. Some very large organizations build their own private microwave networks, rather than rely on circuits leased from carriers. This generally is the case where a number of remote sites must be networked, especially where substantial bandwidth is required. In such situations, the public carriers may be unable to provide the necessary bandwidth and network performance.

  2. A network comprising dedicated circuits leased from one or more public carriers. Such circuits make use of private lines over carrier transmission facilities, bypassing the switches. Many large organizations deployed complex, dedicated T-carrier networks in the 1970s and 1980s. While such networks continue to be supplemented and while such networks continue to be deployed for data communications, VPNs (Virtual Private Networks) generally are preferred for voice communications. A variety of VPN technology alternatives also exist for data communications. See also Private Line, Private Voiceband Network, and VPN.

Private Network-to-Network Interface


Private Networks Marketing

A Northern Telecom term which defines their organization for making and selling all telecom switches, except central offices. These products include the Meridian 1 PBX family, residential and business telephone sets, including Norstar and data communications.

Private Peering Point

A privately-owned packet-switching center at which ISPs exchange traffic, avoiding the cost of doing so through the more traditional NAPs (Network Access Points). See Peering for a more thorough explanation.

Private Subscriber Network

A virtual private network service supported by Public Packet Switched Service (PPSS) and incorporating interLATA transmission facilities owned or leased by the customer for private traffic. A Bellcore definition.

Private System Identifier

PSID. An signaling identifier sent from a private cell site associated with a Wireless Office Telecommunications System (WOTS). The cell phone display shows the name of the company, rather than the name of the carrier. The PSID is defined in IS-136. See also IS-136 and Wireless Office Telecommunications System.

Private Use Network

Two or more private line channels contracted for use by a customer and restricted for use by that customer only.

Private Voiceband Network

A network that is made up of voice band circuits, and sometimes switching arrangements, for the exclusive use of one customer. These networks can be nationwide in scope and typically serve large corporations or government agencies.

Private Wire

A private line. Derives its name from the old telegraph days when messages were carried on wires that strung across the nation.

Privilege elevation

A network security term. The ability of a user to gain unauthorized privileges on a machine or network. An example of privilege elevation would be an unprivileged user who could contrive a way to be added to the Administrator's group.


The access rights to a directory, file or program over a local area network. Typically read, write, delete, create and execute.


See Preferred Roaming List.


PRivate Management Domain. An X.400 Message Handling System private organization mail system. Example: NASAmail.


A Bluetooth term. Pseudo Random Noise Generation.

Pro Forma

Pro forma is a financial term. It is the presentation of data, such as a balance sheet or an income statement, where certain amounts are hypothetical. For example a pro forma balance sheet might show a debt issue that has been proposed but has not yet been consummated, or a pro forma income statement might reflect a merger that has not yet been completed. Pro forma can also mean deviating from established financial practices. Here's the history. In the late 1990s the Financial Accounting Standards Board suggested that software companies adopt an accounting practice it called 97-02. That was meant to assure that companies ” some with pretty aggressive sales cultures ” book revenue on shipped, or fully received wares, not just on orders. The SEC then looked at 97- 02 and ” with the laudable intention of providing investors with a standardized measuring stick for assessing company revenue across all industries ” decided that the it was broadly applicable . So, early in 2000, the SEC propagated "Staff Accounting Bulletin 101," or SAB 101, which essentially made 97-02 the accounting standard for all publicly traded companies in the U.S. SAB 101 became mandatory as of the December quarter. But, the trouble is, some companies have very complicated business models, and many of them ” along with some of their analysts and investors ” simply don't believe that SAB 101 fairly reflects their business activities. Under SAB 101 accounting standards, a company has to wait until a contract is completely fulfilled before it can book proceeds from the contract as revenue. But some companies say software contracts, for instance, sometimes take years to fulfill, because they often include customization, service agreements, product updates and other over-time add-ons. Companies, given pressure to meet or beat the Street's estimates, want to give investors a more dynamic picture of their quarterly business activity, especially when they honestly view the proceeds of orders as, well, money in bank, whether it has been received or not. In short, pro forma financial numbers can be basically whatever the company wishes to report. Share buyer, beware.


Taking the initiative. Doing it before someone (most likely your competition) forces you to do it. The word is currently in vogue among those people who believe the telephone companies should do all the positive, forward-looking actions before the competition does them and wins the customers and gets the public kudos. The word has no real meaning, but serves a purpose as a cry to action. The word actually is grammatically incorrect. The real word is "active." It is the opposite of "reactive."

Probability theory

Probability theory studies the possible outcomes of given events together with their relative likelihoods and distributions. Probability deals with predicting the likelihood of future events. Probability theory is important in picking stocks.


  1. A sensing device, typically about the size and shape of a pencil, that is used to sense various physical conditions such as temperature, humidity, current flow, speed. Usually connected to a meter or oscilloscope which displays the condition being monitored .

  2. An empty message that is sent to reach a particular address to determine if an address can be reached.

Probe Envelope

In X.400, the envelope that encloses a probe in the MTS (Message transfer System). See Probe.

Problem Tracking Report

PTR. A report maintained by a manufacturer in its Problem Tracking Database that describes a specific reproducible product defect or anomaly with a product. A PTR is also used to document a request for a feature enhancement. Information includes PTR number, problem description, PTR priority, system configuration and steps for reproducing the problem.


A software application. Any activity or systematic sequence of operations that produces a specified result. Typically, a computer function that consists of, or involves, procedure code, data storage and an interface for communicating with other processes.

Process Manufacturing

The making of things. This contrasts with flow manufacturing which is working on something ” like oil ” that flows through a production process.

Processing Delay

In data communications, the time taken by a computer to operate on an inbound message and return a response; frequently not accounted for in complaints of telecommunications response time problems.

Processing Gain

In a spread spectrum transmission system, the original information signal is combined with a pseudo random correlating , or spreading code. The more random and the greater the length of the code, the more robust the resulting spread spectrum signal is against interference and interception. A measure of this robustness is referred to as processing gain. The FCC requires a minimum of 10 dB processing gain for non-licensed equipment operating in the Part 15 902-928 MHz, 2400-2483 MHz, and 5725-5850 MHz frequency bands. See also CDMA.

Processing, Batch

A method of computer operation in which a number of similar input items are accumulated and sorted for processing. Compare with On-Line or Interactive Processing.


  1. The intelligent central element of a computer or other information handling system. Also called the Central Processing Unit (CPU).

  2. A device which uses amplifiers and filters to "boost," "clean-up" and reprocess signals. Sometimes channel converters demodulate signals in order to accomplish this function. See Channel Converter.

Processor Card

See Smart Card.

Processor Occupancy

The time the telephone system processor is in use. There are two typical demands on the central processor in a telephone system, moving calls around and running self-diagnostics. Be sure you factor in the second when you're trying to figure out how many calls your telephone system processor will handle before it dies.

Processor Power

The number of computations that a computer, microprocessor, or digital signal processor can complete in a fixed time interval. May be measured in MIPS (millions of instructions per second) or MFlops. Typical low-end DSP chips provide up to 10 MFlops; high-end chips 30 or more.

Procurement Lead Time

The interval in months between the initiation of procurement action and receipt into the supply system of the production model (excludes prototypes ) purchased as the result of such actions, and is composed of two elements, production lead time and administrative lead time.




A device that resembles a pencil, but containing a metal tip in an insulated handle with a wire to connect it to a piece of test equipment, such as a VOM (volt-ohm-millimeter). the metal tip is touched to various points in an electrical circuit for measurements and trouble-shooting.


Formed in 1984 as a joint venture of IBM and Sears Roebuck & Company, Prodigy was originally called TRINTEX. The name was changed to Prodigy in 1988, and the company was acquired by employees with the help of International Wireless in 1996. Prodigy used to offer on-line computer services. The company was one of the first to offer such services for a largely flat monthly fee. Recently, Prodigy decided to terminate the activities of 50 staffers who develop "content" for its information service, and instead to link its users to the content of Excite, a Web directory and search engine. Prodigy will now become more a pure Internet Service Provider, offering connections to the Internet.


This is a stupid word. Let's say you've designed something special for one of client ” a piece or hardware or software or a little of both. He likes it. You figure that others will also. So you make it into a product which you can put in your catalog and which others can buy also. Productize also means to turn an idea into a product. You complete the R&D on it, finish the customer documentation, finish the packaging design, assign a name, model number and stocking number. And you make sure that your people in service are ready to help customers. See also BETA.


A set of parameters defining the way a device acts. In the LAN world, a profile is often used by one or more workstations to determine the connections they will have with other devices and those devices they will offer for use by other devices. Often called a login file. Profiles and login files usually work like batch files, automatically executing a number of commands when you turn on the machine.


Method of classifying individuals according to any data category. However, a profile only has significance if it is compared to a base figure (usually a population or a client database).


PRofessional OFfice System. Interactive productivity software developed by IBM that is part of the Virtual Machine (VM) Productivity System and runs under the VM/CMS mainframe system. PROFS is frequently used for electronic mail and is said to give a user an edge in productivity in three areas: business communications (including electronic mail), time management and document handling.


Instructions given to a computer or automated phone system to perform certain tasks. Most vendors improve (update) their software programs continuously. It's a good idea to ask what the deal is with getting updates.

Program Circuit

A voice circuit used for the transmission of radio program materials. It is a telephone circuit which has been equalized to handle a wider range of frequencies than are required for ordinary speech signals.

Program Counter

A device inside a computer which keeps track of which instruction in the program is next, etc.

Program Evaluation Reviews

An activity many of us are consigned to spend our aging years doing. In the early days of our careers, we used to do things ” actually do tasks hands-on. Then many of us, sadly, got "successful." Our jobs then became telling younger people what to do and checking that they do what we told them, or doing something better (hopefully). To do all this, we sit in meetings. We call these meetings "Program Evaluation Reviews."

Program Evaluation Review Technique

PERT. A management tool for graphically displaying projected tasks and milestones, schedules and discrepancies between tasks.

Program File

A file that starts an application or program. A program file has an .EXE, .PIF, .COM, or .BAT filename extension. AKA executable.

Program Information File

PIF. A file that provides information about how Windows should run a non-Windows NT application. PIFs contain such items as the name of the file, a start-up directory, and multitasking options for applications running in 836 enhanced mode. See PIF.

Program Log

Records once kept by a broadcasting station in a public file which provided a record of programs broadcast, program type and program length. The logs also included commercial and public service spots. Broadcasters are no longer required by the FCC to maintain program logs.

Program Logic

The particular sequence of instructions in a program.

Program Store

In an electronic switching office, the semipermanent memory used for the controlling stored program.


In telephony, the ability to change a feature or a function or the extension assigned to a telephone without rewiring .

Programmable Call Forwarding

This feature of a telephone system allows a user to instruct his phone to send all his calls to another phone. That phone might be another extension in the same phone system or it might be another phone number altogether in a different part of the country. This feature is great. You're going to a meeting but don't want to miss that one special call. You can send your calls to a person close to the meeting and ask them to interrupt you if that "special" call comes in. The problem with this feature is that often people forget their phone is on "forwarding" and when they return to their office, they sit around all afternoon waiting for that special call, which got call forwarded elsewhere. There are two ways to overcome this. Some phones have lights or messages on their screens which indicate all calls are being forwarded. Also, some telecom managers program their total phone systems so that twice a day, all call forwarding shall cease and all calls shall return to their original phone.

Programmable Configuration Select

Refers to the EEPROM setup routine which allows jumperless configuration of the system board.

Programmable Logic

A Programmable Logic device is typically a chip that can be reconfigured. It consists of arrays of basic logic gates laid out in a grid of connecting wires. These chips offer the advantage of being able to be reconfigured in minutes rather than the months that is needed to revise the design of a custom-made chip. They are ideally suited for products where flexibility is needed, such as when industry standards are still undetermined. Disadvantages of programmable logic chips include that they are invariably larger due to their inherent inefficiency, which can make them more expensive. See also Custom Chip.

Programmable Memory

Memory that can be both read from and be written into by the processor. Synonym for Random Access Memory ” RAM.

Programmable Terminal

A user terminal that has some limited processing power. Also, intelligent terminal.

Programming Language

A language used by a programmer to develop instructions for the computer. It is translated into machine language by language software called assemblers, compilers and interpreters. Each programming language has its own grammar and syntax.

Programming Overlay

Typically a piece of cutout cardboard, which you place over certain of the keys on a phone or console. When you punch in a certain code, the buttons become what's written on the programming overlay.

Program Sharing

The ability of several users or computers to use a program simultaneously .

Program Store

Permanent memory in a stored program control central office that contains the machine's generic software program, parameters and translations.

Progressive Conference

A PBX feature. Allows the extension user to create conferences of more than three people using the consultation hold and add-on conference features. To create a conference, an extension user typically uses the consultation hold, dials the desired internal or external number and effects an add-on conference. The conference may then be progressively expanded, in this same fashion, to the maximum capability of the phone system offering this feature. A good question to ask before you get sold this feature is "does the conferencing have amplification and balancing?" Without these features, the conferencing conversation will simply get more and more difficult to hear on.

Progressive Dialing

A form of predictive dialing, progressive dialing is slightly more automated than preview dialing. The customer data is not displayed until the number is dialed, giving the agent less time to review it and a shorter time between calls. See also Predictive Dialing and Preview Dialing.

Progressive Display

See Interlaced GIF.

Progressive Tuning

A method of painting pictures on computer monitors or TV screens in which the picture is painted line by line. It is today's most common way of painting a picture or an image on a computer screen.

Project 25

Project 25 is a joint government/industry standard setting effort to develop technical standards for the next generation of two-way communications equipment.

Project Evaluation Review Technique

PERT. A technique for managing a project ” say the installation of a PBX ” which produces a guess at the project's critical path (longest task to complete) and of project milestone completion dates. See PERT.


Programmable Read Only Memory. A PROM is a programmable semiconductor device in which the contents are not intended to be altered during normal operation. PROM acts like nonvolatile memory. When you install an autoboot PROM on a LAN network board, the workstation can boot up from the network server. This is particularly useful for diskless workstations.

Promiscuous Mode

Most Ethernet cards ignore all the packets on the network that aren't destined for them. But in a Remote server ” one serving multiple remote users all calling in over modems ” the Ethernet LAN card has to get access to all the packets and grab those that are meant for it ” so it can pass them over to the remote callers. I assume it's called "promiscuous mode" because it means that the Ethernet card has to have a relationship with all the packets traveling on the local area network. Another application for promiscuous mode is if you want to attach software or hardware to your computer, monitor and analyze all the packets flying around your network. You can set some (but not all) Ethernet cards to promiscuous mode. See also Incestuous Amplification.


According to various dictionaries, "promotion" means to raise in station, status, rank or honor ." Once upon a time, a promotion meant you got a better title, a bigger office and a raise in pay. Today, it means that a software release or your hardware product just made a change in status from alpha test to beta test, or from beta test to general release. See also Alpha Test and Beta Test.


An audible or visible signal to the system user that some process is complete or some user action is required. Also used to signify a need for further input and/or location of needed input. See also the next three definitions.

Prompt Tagging And Encoding

According to Steve Gladstone, author of the book, "Testing Computer Telephony Systems," (available from 212-691-8215) many test applications require the test system "know" which prompt is being played by the computer telephony system. This is often accomplished by prompt tagging, also known as prompt encoding. Prompt tagging has the computer telephony system play-out an audio tone that can be heard by the test system with each prompt that is played. Prompt tagging is relatively inexpensive to perform, and inexpensive to automate. Prompt tagging can be accomplished in two ways, either by inserting tones into actual user prompts ("insert" mode), or by having a special programmatic switchable test mode that may be toggled on/off by the computer telephony system that will play out a tone sequence before or after each prompt is played ("append" mode).


Visually or audibly indicating to a user of a telephony device that a call has reached (and been accepted by) the device and is capable of being answered. This is typically done by ringing the device, flashing a lamp, or presenting a message on the device display.


  1. Recorded instructions delivered by voice processing units. Prompts may include MENUS or other information that is played each time you get into the system.

  2. Messages from the computer instructing the user on how to use the system. See Menu and Audio Menu.

Proof Of Concept

You're at a trade show. You go to a booth . You see some great new technology. You can't buy it. It's simply a demonstration of new technology. What's called "proof of concept." It proves that the idea works. It doesn't mean there's a market for it. The idea of "proof of concept" is to excite people ” customers or security analysts. Maybe someone will place a big order or buy the company's stock?

Propagation Delay

The length of time it takes a signal to travel from transmitter to receiver across a circuit, at the most fundamental level, propagation delay is a factor of the finite speed at which electromagnetic signals can travel through a transmission medium. The basis for comparison is the velocity of light in a vacuum , which is 300,000 (actu- ally 299,792) kilometers per second, or 186,280 miles per second. Signal propagation is approximately 222,000 kilometers per second in an optical fiber, depending on factors such as impurities in the fiber core, temperature, and the refractive index of the cladding. Signal propagation in CAT 5 copper wire is roughly 200,000 kilometers per second, depending on a variety of factors including the nature of the dielectric insulating material.

Propagation delay is a huge issue in satellite communications. Given the fact that the originating signal must travel from the earth station 22,300 miles up to the satellite and 22,300 miles back down, a roundtrip (i.e., up and down in one direction) transmission takes about .25 seconds. When you add the time imposed for signal processing at the transmitting earth station (i.e., satellite dish), the space station (i.e., satellite), and the receiving earth station, the total delay is about .32 seconds. Therefore, it takes at least .64 seconds to get a response to your query. This level of propagation delay renders satellite communications ineffective for highly interactive data communications applications, as the users get really bored. Satellite communications also is highly aggravating for voice communications.

This satellite example illustrates the fact that propagation delay is affected by not only the characteristics of the physical transmission medium, but also the nature and number of various devices associated with the circuit. Examples include terminal equipment, bridges, hubs, switches, and routers. Such devices accomplish various processes, including buffering, queueing, protocol conversion, and error detection and correction. Each of these processes takes some amount of time, which generally is sensitive to the complexity of the process. Buffering and queueing of data is a means of dealing with issues of congestion in the network, or a given network element, and the level of delay imposed on the data is variable in nature, sensitive to the level of congestion existing at a given moment in time.

Propagation delay is a factor of great significance in many data communications protocols (e.g., Synchronous Data Link Control, or SDLC), where there may be a tight timing relationship between the transmitter and the receiver across the circuit. These timing considerations are significant in the control of access to the transmission medium, and in the detection and correction of errors in transmission. See also Path Delay Value and Velocity of Light.

Propagation Delay Skew

The difference between the propagation delay on the fastest and slowest pairs in a UTP cable. When one pair is much higher or lower in delay than the others, a very high skew may result.

Propagation Time

Time required for an electrical wave to travel between two points over a transmission circuit. See also Propagation Delay.

Propagation Velocity

The speed at which electrons or photons travel through a transmission medium. See also Propagation Delay.

Propeller Head

An excessively technical person, whose social skills are lacking.


Windows 95 treats all objects, such as windows, icons, applications, disk drives, documents, folders, modems, and printers as self-contained objects. Each object has its own properties, such as the object's name, size position on-screen, and color, among others. You can change an object's properties using the properties dialog box.

Property Management Interface

PMI. A telephone system's ability to talk to a hotel's computer system.

Proportional Font

A font in which different characters have varying widths. All magazines and newspapers are printed in proportional characters, which make reading easier. By contrast, in a monospaced font, such as one on an old typewriter, all characters have the same widths.


If something is proprietary it means it will only work with one vendor's equipment. See the next three definitions.

Proprietary LAN

A LAN (Local Area Network) that runs the equipment of only one vendor. A proprietary LAN, for example, cannot join IBM PCs to DEC minicomputers. Some people say such LANs are more "bug-free" because they have only one vendors' wares to deal with. They also tend to be more expensive. They also tend to tie you to one vendor, although some makers are now coming out with bridges which connect proprietary LANs to non-proprietary LANs. Since Ethernet and the Internet, proprietary LANs are effectively dead.

Proprietary Network

A network developed by a vendor that is not based on protocols approved by standards body or on standards that are "open." Typically, you won't be able to connect to a network with any equipment other than that made by the manufacturer who created it.

Proprietary Telephone Sets

Proprietary telephones are feature phones that are specific to a particular make of PBX, ACD or other switching system. They may be digital or analog. As they are custom designed for that system, they have non-standard electrical interfaces and have non-standard protocols to communicate between the telephone and the switch. This has several implications:

  1. You can't take a proprietary phone from one switch and expect it to run on another switch. It won't.

  2. Proprietary phones are expensive, and are highly profitable to their makers. Hence the manufacturers' insistence on keeping them proprietary.

  3. Signaling between proprietary phones and their switches is richer than signaling between switches and single line analog phones. As a result, it's preferable to integrate voice mail and automated attendants through proprietary phones. Sometimes the manufacturer of the switch will divulge his secret signaling scheme. Other times he won't. Most times he wont. And you, as a voice mail or auto attendant manufacturer have to reverse engineer it, which is sometimes successful. ISDN is actually the first attempt to make "proprietary" sets standard. So far, only a few manufacturers have used ISDN-like phones as their proprietary phones.


In speech recognition, prosodics refers to the parts of the sentence the speaker emphasizes. For example, "I am going to Paris" with emphasis on the "I" means that only one person is going to Paris and therefore only one ticket should be issued. See also Prosody .


Intonation. In text to speech, prosody refers to how natural it sounds ” the ups and downs of the sentence. See also Prosodics.


The opposite of Retrospective or Retroactive. Most regulatory commission rate cases are prospective, which means they relate to prices and things in the future.

Some rate cases, however, are retroactive or retrospective, which means they apply to prices and things in the past. Most of these decisions involve forcing the company to return money to its subscribers in the form of a refund. Interestingly ” try this one ” most retroactive commission decisions are prospectively retroactive. In other words, they only take effect some time in the future, when the decision is voted upon by all the commission members .


UNIX software which helps you search archives connected to the Internet. Prospero uses a virtual file system which enables users to transparently view directions and retrieve files. In short, Prospero is a distributed directory service and file system that allows users to construct customized views of available resources while taking advantage of the structure imposed by others.


A cross between a professional and a consumer. Imagine you make a camera that's too good and too expensive for consumers, but too cheap for professionals. Therefore the camera is a now classed as being for prosumers ” whoever they are. I guess they're rich consumers, or poor professionals.

Protected Area

A zone defined by a station's FCC license which is legally protected from interference (on the station's authorized channel or channels) by all other stations.

Protected Distribution System

PDS. This is a US Federal Government definition: A wireline or fiber-optics telecommunication system which includes adequate acoustic, electrical, electromagnetic, and physical safeguards to permit its use for the unencrypted transmission of classified information. A complete protected distribution system includes the subscriber and terminal equipment and the interconnecting lines.

Protected Memory

An operating system feature that keeps one program from grabbing memory set aside for another program and corrupting data to that program.

Protected Memory Allocation Mode

A mode in which the operating system (the OS) reserves memory for itself. By switching the processor to this mode, the OS can execute several programs at once, transcending the one-megabyte limit normally enforced on the processor.

Protected Mode

A computer's operating mode that is capable of addressing extended memory directly. The operating mode for the Intel 80286 and higher processors (the 80386, 80486 and Pentium) that supports multi tasking, data security, and virtual memory. The 80286 processor can run in either of two modes: real or protected. In real mode, it emulates an 8086 (it accesses a maximum of 640KB of RAM and runs only one software application at a time). Protected mode allows the 80286 processor to access up to 16MB of memory. It uses a 24-bit address bus. Since a bit can have one of two values, raising the base number of 2 to the power of 24 is equal to 16,777,316 unique memory addresses. Each memory address can store one byte of information (16,777,216 bytes equals 16MB). Protected mode operation also makes it possible to run more than one application at once and to handle more processes because more memory is available. Processes can be requests from an operating system or an application to perform disk I/O, memory management, printing, or other functions. Processes are assigned priority numbers in protected mode. The processor gives priority to those with higher numbers. Operating system processes always have higher priority than application processes. See also Real Mode and Virtual 8086 Mode.

Protective Connecting Arrangement

PCA. A device leased from the telephone company and placed between your own (customer-provided) telephone equipment and the lines of the telephone company. The idea was to protect their lines from your junky equipment. No instance/case was ever proven of harm occurring to the network from faulty customer-provided equipment and the PCAs were thrown out and replaced by the FCC's Part 68 Registration Program. Under this program, customer-owned equipment which passes FCC tests can be registered and connected directly to the phone network without these devices. The phone industry eventually refunded most of the fees it charged on the PCAs. NATA and many manufacturers claimed the PCAs were designed to prevent the growth of the interconnect or customer-owned phone industry. They were probably right. The question is now moot, since the charges and the devices no longer exist, except in a museum or attached to very old equipment. See also Protective Coupling Arrangement and PCA.

Protective Coupling Arrangement

PCA. A device placed between the phone company's trunks and your particular telephone gadget. The objective of the PCA is to isolate the telephone company's lines from your equipment and thus protect their lines from your equipment. The device is not needed if your equipment has passed FCC approval ” under Part 68 of the FCC's rules. See also Protective Connecting Arrangement, which is another term for the same thing.

Protector Block

A device connected to an exchange access line to protect connected equipment from over-voltage and/or over-current. Hazardous voltages and currents are shunted to ground. In other words, a surge protector limits unwanted surge voltages to values which can be handled safely by the insulation on inside wire and by the electronics in the customer terminal equipment. Protectors are very important in high-lightning areas, where they (theoretically) keep wires and phones from melting, phone systems from being blown off the wall, and end users from being electrocuted.

The original protectors were based on carbon blocks which effectively blocked aberrant voltage surges. Subsequently, gas tube protectors were used. Solid state protectors were the third generation. Improvements in the speed of of reacting to incoming high voltage and high currents have been at the forefront of the improvements in technology. While all variety of protectors currently are in place, those currently being deployed are either solid- state or hybrids, which incorporate both gas tube and solid-state technology. Protectors often are an element of a multi-function NID (Network Interface Device), also known as a NIU (Network Interface Unit), which acts as the point of demarcation between the local exchange carrier and the customer premise.

Protector Frame

A frame, usually part of the MDF, that serves as termination for loop cables. The protector frame contains electrical protection devices that normally provide conducting paths, but will break down and electrically isolate a loop from the switching equipment when an abnormally high voltage contact occurs.


PRocedure Oriented Type Enforcing Language. Protel is a block-structured, type- enforcing, high level, software language that enables extensive type checking on the source code at compile time. It was developed at Bell Northern Research, a subsidiary of Northern Telecom. Protel is used in the DMS-100, a family of Northern Telecom central office telephone switches. Both the central control CPU and the DMS SuperNode CPU are programmed in Protel.


Protection. See Protector Block.


Protocols define the rules by which devices talk with each other, or more formally , a protocol is a set of rules governing the format of messages that are exchanged between computers and people. Imagine making a phone call. You pick up the phone, listen for dial tone, then punch out some buttons on your phone, then listen for ringing and for an answer. The person says "Hello." You say "Hello." Then you talk... What you're doing is following a protocol to make a call. When computers make calls between themselves ” to transfer data, for example ” they follow a protocol. They aren't smart, like you and I. They can't distinguish between dial tone and fast busies, unless those sounds and signals are specifically defined. A protocol defines the procedure for adding order to the exchange of data (i.e. a "conversation.") A protocol is a specific set of rules, procedures or conventions relating to format and timing of data transmission between two devices. It is a standard procedure that two data devices must accept and use to be able to understand each other. The protocols for data communications cover such things as framing, error handling, transparency and line control. There are three basic types of protocol: character- oriented, byte-oriented and bit-oriented.

Protocols break a file into equal parts called blocks or packets. These packets are sent and the receiving computer checks the arriving packet and sends an acknowledgement (ACK) back to the sending computer. Because modems use phone lines to transfer data, noise or interference on the line will often mess up the block. When a block is damaged in transit, an error occurs. The purpose of a protocol is to set up a mathematical way of measuring if the block came through accurately. And if it didn't, ask the distant end to re-transmit the block until it gets it right. See PROTOCOLS for a list of the more common protocols. See the following protocol definitions. See also Handshaking and Line Discipline.

Protocol Analyzer

A specialized computer and/or program that hooks into a LAN and analyzes its traffic. Good protocol analyzers can record and display data on all levels of traffic on a LAN cable, from the lowest media access control packets to NetBIOS commands and application data. They are excellent for diagnosing network problems, but they require some expertise, as their data output can be obscure.

Protocol Control

Protocol Control is a mechanism which a given application protocol may employ to determine or control the performance and health of the application. Example, protocol liveness may require that protocol control information be sent at some minimum rate; some applications may become intolerable to users if they are unable to send at least at some minimum rate. See MCR.

Protocol Control Information

PCI. the protocol information added by an OSI (Open Systems Interconnection) entity to the service data unit passed down from the layer above, all together forming a PDU (Protocol Data Unit).

Protocol Conversion

A data communications procedure which permits computers operating with different protocols to communicate with each other. See Protocol and Protocol Converter.

Protocol Converter

A device which does protocol conversion. It's your classic "black box." Glasgal Communications defines a protocol converter as any device which translates a binary data stream from one format to another according to a fixed algorithm. Compare with bridge and gateway, which are different animals and may contain protocol converters...and more.

Protocol Data Unit

See PDU.

Protocol Dependent Routing

Any routing method in which routing decisions are made on the basis of information provided by the specific LAN protocol used by the communicating devices. TCP/IP and DECnet routers are protocol dependent routers. So are so-called multi protocol routers, because they must support each protocol running in the network. See also Protocol Independent Routing.

Protocol Filtering

A feature available in some network bridges which allows it to be programmed to always forward or reject transmissions associated which specified protocols.

Protocol Independent Multicast - Dense Mode PIM-DM is a multicast routing protocol designed for networks that have a large number of multicast subscribers and enough bandwidth to support the multicast sessions. PIM-DM uses a flood and prune technique to reach all parts of the network to inform routers of the multicast session. Computers that want to join the multicast session contact the nearest router using the Internet Group Management Protocol (IGMP) and ask to be added to a specific multicast group. The router adds them to the group and builds a delivery tree that links the multicast sender to the computers that have joined the multicast group. Any paths to routers that do not have computers that want to join the multicast session are removed or "pruned" from the delivery tree until only the paths to those computers who have joined the multicast group are left. PIM-DM sends multicast packets to routers in the delivery tree, which are then delivered to only the computers that have joined the multicast group. PIM-DM uses reverse path forwarding (RPF) to distribute the multicast packets to the delivery tree and to keep network loops from forming in the process. The router implementing RPF receives a multicast packet from the multicast sender and compares the destination IP address of the packet to the delivery tree. If the IP address is in the delivery tree routing table the packet is forwarded, if not it is discarded. PIM-DM is similar to other multicast routing protocols such as the Distance Vector Multicast Routing Protocol ( DVMRP), but unlike other protocols PIM-DM uses any underlying unicast routing protocol such as RIP, OSPF, BGP, etc. to build a multicast delivery tree. The ability to work with multiple unicast protocols allows PIM-DM to work across mixed network infrastructures that are present in large networks. The above courtesy Alcatel.

Protocol Independent Router

A routing device that provides the functionality of protocol specific routers such as TCP/IP or DECnet routers but is independent of protocols. In addition to routing "routable" protocols like TCP/IP, DECnet or XNS, it routes IBM protocols which are not routable. The protocol independent router combines the latest in computer hardware with the new advanced routing technologies such as SPF (Shortest Path First) and IS-IS (OSI routing standard). It represents an alternative to conventional routers that use old routing technologies and are protocol dependent. Protocol independent routers provide easy-to-install-and-use enterprise-wide networks in a token ring or Ethernet environment.

Protocol Independent Routing

A routing method in which routing decisions are made without reference to the protocol being used by the communicating devices. Protocol independent routers provide the functionality of protocol specific routers such as TCP/IP or DECnet routers, but can also route non-routable protocols. See also Protocol Independent Router.

Protocol Mapper

Protocol Mappers are employed where a logical server is delivering a proprietary CTI protocol and / or providing connections through a proprietary transport protocol. Mappers deliver one of the specified CTI Protocols alter first mapping, or translating, from the non-specified, proprietary protocol.

Protocol Mapper Device

Implementation of a Protocol Mapper as device which sits on a data connection and is transparent to the logical client. See Protocol Mapper.

Protocol Mapper Code

Implementation of a Protocol Mapper as a software component. Mapper Code components mimic transport protocol stack implementation, and, using an appropriate R/W interface, are layered above any transport protocol stack and are transparent to Client Implementations. See Protocol Mapper.

Protocol Stack

First, read the definition on what a protocol is. Understand that a protocol is a specific set of rules, procedures or conventions relating to format and timing of transmission between two devices. Protocol defines the rules for "conversations" ” voice, data, video, etc. ” between two computers. A protocol stack is basically a collection of modules of software that together combine to produce the software that enables the protocol to work, i.e. to allow communications between dissimilar computer devices. It is called a stack because the software modules are piled on top of each other. The process of communicating typically starts at the bottom of the pile and works itself up. Each software module typically (not always) needs the one below it. Sometimes one big protocol stack ” such as the one for H.323 ” might include specific protocol standards further down the stack. The TCP/IP protocol stack includes such protocols as TCP, IP, FTP, SMTP, telnet, and so on. A protocol stack is also called a protocol family or protocol suite. See Protocol.

Protocol Suite

A hierarchical set of related protocols.

Protocol Translator

Network device or software that converts one protocol into another similar protocol.


For an explanation of protocols, see Protocol. Here are the more common PC protocol types:


Bell 103: Low Speed (300 baud)

Bell 212: Low Speed (1200bps)

ITU-T V.22bis: Medium (2400bps)

ITU-T V.32: Medium Speed (9600bps)

ITU-T V.32bis: High Speed (14,400bps)

ITU-T V.34: High Speed (28,800bps)


Microcom Network Protocol (MNP)

ITU-T V.42 (Includes LAP-M & MNP)



ITU-T V.42bis

All data compression requires an underlying error control protocol.


Kermit: 7-bit data path, quotes control characters.

XMODEM: 8 bit data path, ACK/NAK protocol. YMODEM: 8-bit data path, batch capability.

ZMODEM: 8-bit data path, quotes some control characters.


A Proton is a heavy subatomic particle that carries a positive charge. Protons are found in the nucleus of the atom.


The development of a model that displays the appearance and behavior (look and feel) of an application to be built. A prototype may only demonstrate the application's. It may also demonstrate navigation and user controls, or it may even accept input data that can be stored in and retrieved from a simulated database. (See also iterative development.)


A process that represents an interface between the Sun Solaris Teleservices platform and an installed telephone device, such as a telephone line or a fax machine. Multiple instances of a provider can be configured, each based on the same information. Each configuration is identified by a unique primary alias. A primary alias is the primary label used to prefer to a provider configuration. The primary alias is a provider's default and primary name. This definition courtesy Sun.

Provider of Last Resort

The service provider that is obligated to provide basic service to a customer in the absence of the availability or willingness of an alternative competitive service provider to do so. The term generally applies to the telecommunications industry, although it now also applies to the electric industry. In the days of monopolistic utilities, when there was only one local service provider, there was no issue. Since competition has been introduced in the local exchange, however, some service provider must serve as the provider of last resort, regardless of profitability (or the lack thereof). The provider of last resort is obligated to provide basic service (i.e., local dial tone) to customers within its franchised serving areas in the event that either no other service provider is available or no other service provider is willing to provide service. Examples include people and companies with terrible credit records, people who require lifeline service, and people who need TDDs (Telecommunications Devices for the Deaf). Providing such services is decidedly unprofitable, but some company must do it as a matter of social policy. In the telecommunications domain, the provider of last resort is the ILEC (Incumbent Local Exchange Carrier); in areas where the electric industry has been deregulated, it is the incumbent electric utility. The concept is closely tied to that of Universal Service. See also Universal Service.


The act of supplying telecommunications service to a user, including all associated transmission, wiring, and equipment. The telephone industry defines provisioning as an engineering term referring to the act of providing sufficient quantities of switching equipment to meet established service standards. In NS/EP telecommunication services, "provisioning" and "initiation" are synonymous and include altering the state of an existing priority service or capability.

Proximity sensor

A device that detects the presence of an object and signals another device. Proximity sensors are often used on manufacturing lines to alert robots or routing devices on a conveyor to the presence of an object.


  1. A proxy is an intermediate application program that acts as both a client and a server. A proxy runs on a gateway that relays packets between a other trusted clients and an untrusted host, perhaps making protocol translations in the process. A proxy accepts requests from the trusted client for specific Internet services and then acts on behalf of this client (in other words, serves acts as proxy for this client) by establishing a connection for the requested service. The request appears to originate from the gateway running the proxy, rather directly than from the client. All application-level gateways use application- specific proxies (that is, modified versions of specific TCP/IP services). Most circuit-level gateways use pipe, or generic, proxies that offer the same forwarding service but support most TCP/IP services. A "transparent proxy" makes no modifications to a request from an origin client other than what absolutely is required to identification and authentication. A "non-transparent proxy" modifies requests from the origin client and/or responses from the origin server in order to provide additional services. See Client, Dual-Homed Gateway, Proxy Server, and Server.

  2. A software agent that acts on behalf of a user. Also, the mechanism whereby one system "fronts for" another system in responding to protocol requests. Proxy systems are used in network management to avoid having to implement full protocol stacks in simple devices, such as modems. In SNMP, a proxy is a device which performs SNMP functionality for a separate managed device. The amount of responsibility may vary. Proxy ARPing refers to address recognition for another unit with SNMP capability, while a proxy agent provides an external SNMP agent for a managed device which does not have SNMP capability.

Proxy ARP

The technique in which one machine, usually a router, answers ARP requests intended for another machine. By "faking" its identity, the router accepts responsibility for routing packets to the "real" destination. Proxy ARP allows a site to use a single IP address with two physical networks. Subnetting would normally be a better solution.

Proxy Server

A proxy is an application running on a gateway that relays packets between a trusted client and an untrusted host. A proxy server is software that runs on a PC and is basically a corporate telephone system for the Internet. Here's what I mean: A telephone system's main job is to allow a large number of people access to a few number of phone lines. Example: we have 100 people in our firm. But we have only 30 outside phone lines. To grab an outside phone line you dial 9 and then dial your number. When the 31st person tries to grab an outside line, he gets a busy. If this happens a lot, we install more phone lines. The reason we have fewer phone lines than people is clearly economic. We save money that way. All phone systems work that way. A proxy server performs the same function. Let's say your company is connected to the Internet on a single high-speed digital line, e.g. a T-1. The provider of this line gives you a certain number of distinct and different IP addresses which you can use ” just like our phone system gives us 30 distinct and different phone lines. Since most firms will have fewer IP addresses than they have people wanting to use the Internet, they'll need a proxy server to act like a phone system ” allocating precious IP addresses as the people want them. This process is called address translation. A proxy server is typically also a firewall ” that means it keeps unwanted intrusion from the Internet getting into your corporate network. Thus, the fire- wall's IP addresses function as a proxy addresses. Proxy servers provide extra security by replacing calls to insecure systems' subroutines. Proxy servers also allow companies to provide World Wide Web access to selected people, restricting some, allowing others through the firewall ” just like a phone system restricts some people from making long distance calls, etc. Acting as behind-the-scenes directors, proxy servers can also help distribute processing load and provide an added layer of security. A proxy server could also cache some of the material from popular Web sites, saving access time and phone monies.

In short, a proxy server lets your employees access the Internet right from their desktop PCs over a shared, managed, and secure connection to the Internet. No more running modems to desktops ” a slow, expensive solution. That connection to the Net can be "nailed up," like a T-1 or equivalent, or it can even be an on-demand connection. That is, if there is no traffic moving over the connection for a period of time, a proxy server can turn off the connection so your company isn't wasting dollars on an Internet connection not being used. And the proxy would then re-establish the connection immediately when a user tried to access a web site.

According to Microsoft, a proxy server has the following advantages:

  1. It accelerates access to the Internet with intelligent caching ” no more World Wide Wait!

  2. It protects your Intranet in ways a packet filtering router can not.

  3. It blocks access to undesirable sites and provides other easy-to-use management features.

  4. It saves money by consolidating and making the most of your Internet connection. See also Router-based Firewall and Dual-Homed Gateway.


Primary Reference Source. The master clocking source in a network. Other, distributed devices derive their clocking from the PRS in order that the entire network and all associated network elements maintain synchronization. See also Clock, Stratum Level and Timing.


Post Release Software Manager.




Paging Systems.


Power Sum-Attenuation-to-Crosstalk Ratio. A measurement of the strength of the data signal in one pair compared to one or more other pairs in a common cable. PSACR is measured in dB (decibels). See also ACR and dB.


Power Sum-Near End CrossTalk. A measurement of the extent to which one cable pair resists interference generated by one or more other pairs in a common cable. PS- NEXT is measured in dB (deciBels). See also dB and NEXT.

Ps and Qs

In English pubs, ale is ordered by pints and quarts. In old England, when customers got unruly, the bartender would yell at them to mind their own pints and quarts and settle down. It's where we get the phrase "mind your Ps and Qs."


IBM Personal System/2 personal computer.


Professoinal Services Automation.


AT&T's Processor-to-Switch Applications Interface. See also ASAI and SCAI.


A growing number of people are using their hand-held organizers to help them practice their religion. The New York Times coined the word on February 7, 2002. Neat, eh?


Public Safety Answering Point. PSAPs are customarily segmented as "primary," "secondary" and so on. The primary PSAP is the first contact a 911 caller will get. Here, the PSAP operator verifies or obtains the caller's whereabouts (called locational information), determines the nature of the emergency and decides which emergency response teams should be notified. ALI (Automatic Location Information), contained in a database, provides supplemental information for purposes of locating the caller, determining if hazardous materials are located at the subject, and so on. In some instances, the primary PSAP may dispatch aid. In most cases, the caller is then conferenced or transferred to a secondary PSAP from which help will be dispatched. Secondary PSAPs might be located at fire dispatch areas, municipal police force headquarters or ambulance dispatch centers. Often the primary PSAP will answer for an entire region. See also 911, Enhanced 911 and ALI.


Public Service Commission. Also known as Public Utility Commission. It's the state agency charged with regulating the local phone company utility. In reality, there are only two things the PSC can do:

  1. Allow the phone company to increase its prices, and

  2. Restrict competition to the phone company by creating all sorts of restrictive rules and regulations. As competition in the telecommunications industry grows ” chiefly because of Federal rulings ” the state PSCs are losing their power. This bothers them.


See Power Spectral Density Mask.

PSD Mask

See Power Spectral Density.


Public Switched Digital Service. A BOC service. AT&T Circuit Switched Digital Capability (CSDC), also known commercially as AT&T's Accunet Switched 56 service. It allows a full-duplex, dial up, 56-Kbit/s digital circuits on an end-to-end basis.


Power Sum Equal Level Far End Crosstalk. A calculation derived from an algebraic summation of the individual ELFEXT effects on each pair by the other three pairs. There are four PSELFEXT results for each end.

Pseudo Automatic Location Identification

pALI. A telephone network database record that holds the location of a wireless cell or sector (whereas an ALI contains the location of a wireline telephone). In wireless E-911, the pALI is used to provide a rough estimate of the wireless caller's location. See Position Determination Technology.

Pseudo Automatic Number Identification

pANI. Also called Routing Number. A number employed in wireless E-911 call setup that can be used to route the call to an appropriate public service answering point (PSAP). The pANI generally identifies the cell/sector from which the call originates, whereas an ANI carries the actual telephone number of a wireline caller.

Pseudo Code

P-CODE. Program code unrelated to the hardware of a particular computer and requiring conversion to the code used by the computer before the program can be executed or acted upon. Here's a more technical explanation. Pseudo Code is a compiled program written for a hypothetical processor and interpreted at runtime by a P-code interpreter written for a native environment. P-code has many objectives in its different implementations, most often portability and space savings.

Pseudo Flaw

A loophole planted in an operating system as a trap for intruders.

Pseudo Lite

A ground based differential GPS (Global Positioning System) which transmits a signal like that of an actual GPS satellite, and can be used for ranging .

Pseudo Random

A superficially random process or series of events which follow some obscure algorithm.

Pseudo Random Bit Pattern

A test pattern consisting of 511 or 2,047 bits ensuring that all possible bit combinations can pass through a network without error.

Pseudo Random Number Generator

A device which generates apparently random numbers based upon some algorithm.

Pseudo Random Test Signal

A pseudo random test signal is a signal consisting of a bit sequence that approximates a random signal.

Pseudo Range

A distance measurement based on the correlation of a GPS (Global Positioning System) satellite transmitted code and the local receiver's reference code, that has not been corrected for errors in synchronization between the transmitter's clock and the receiver's clock.

Pseudo Ternary

A term used in ISDN Basic rate interface data coding. Refers to three encoded signal levels representing two-level binary data (binary "1"s are represented by no line signal, and binary "O"s by alternating positive and negative pulses).


  1. Packet Switching Interface.

  2. Pounds per square inch, a unit of air pressure. Telephone cables that are pressurized with nitrogen (because it's not corrosive ) are kept at a pressure of around ten to 15 PSI.


Private System IDentifier.


Phase Shift Keying. A method of modulating the phase of a signal to carry information. See Phase Modulation.


Phase Shift Modulation, another way of saying Phase Shift Keying. See Phase Shift Keying.


  1. Packet Switch Node. The contemporary term for the IMPs (Interface Message Processors) originally used in the ARPANET and MILNET, which were the predecessors to what we now call the Internet. PSNs are intelligent switching nodes, which may be in the form of either packet switches or routers.

  2. Processor Serial Number. Intel created quite a stir when it released the Pentium III processor in February 1999. Each Pentium III processor chip has a PSN embedded into it during the manufacturing process. The PSN serves as a unique identifier for the processor, and the associated system of which it is a part. If enabled by the client system user, the PSN is provided to the server on request. In combination with other identifiers such as login names and passwords, the PSN provides an additional authentication mechanism and, thereby, an additional level of security. In an e-commerce application, the PSN can be matched up with other personal information as a means of ensuring that you are who you say you are, and that the transaction, therefore, is legitimate . The PSN also provides corporate IT managers with the ability to inventory and track Pentium III computers through the network, without having to track them down physically and enter serial numbers either manually or through the use of a bar code scanner. Privacy advocates created a minor furor when they suggested that the PSN was a means of tracking your activities on the World Wide Web. The furor subsided, but the issue remains.


(Power sum NEXT. A measurement for qualifying cabling intended to support 4-pair transmission schemes such as Gigabit Ethernet. It is an algebraic summation of the individual NEXT effects on any one pair by the other three pairs.


  1. PCS Service Provider.

  2. Payphone Service Provider.

  3. Purchase Service Provider. A company which provides ecommerce services for a fee or a commission. I've heard fees of $1 a transaction and also 25% of the total value of the sale.


Packet Switched Public Data Network. A PSPDN is a general purpose data network using packet transmission techniques, as opposed to circuit techniques as used for instance in the PSTN. It is used primarily for communications with or between computers.


Perceptual Speech Quality Measure. An automated method which rates voice quality based on comparison of a predefined speech sample before and after transmission through a codec and/or network. P.861 describes Perceptual Speech Quality Measure (PSQM) as the automated rating method. The PSQM algorithm attempts to measure distortion in an "internal psychoacoustic domain," which mimics the sound perception of humans in real-life situations. The PSQM conversion of signals in the physical domain (e.g., frequency and time) to the more meaningful psychoacoustic domain, the process provides a quantifiable, objective rating, rather than the subjective rating offered by the P.800 specification. The source signal is specified in ITU-T P.50 as an artificial voice with an active speech level of -20dBm, which includes both male and female genders, and which reproduces many the essential characteristics of human speech. The output of the test process is a PSQM value ranging from 0 to 6.5, with 0 being perfect quality and 6.5 being the highest level of signal degradation. Note that the PSQM value of PCM (Pulse Code Modulation), the traditional method for converting voice signals from analog to digital format in PSTN applications, is 0.5. This value reflects a relatively minor difference between the analog input and the uncompressed digital output of the encoding process. See also P.861 and Toll Quality.


An instrument arranged to give visual indication corresponding to the aural effect of disturbing voltages of various frequencies. A psophometer usually incorporates a weighting network, the characteristics of which differ according to the type of circuit under consideration; e.g., high-quality music or commercial speech circuits.


Petabit Switch Router. See also Petabyte.


Private Signaling System number 1. The formal name for QSIG, as standardized on a worldwide basis by the ISO (International Organization for Standardization) and the IEC (International Electrotechnical Commission). PSS1 is an ISDN-based protocol for signaling between nodes of a Private Integrated Services Network (PISN). QSIG predates PSS1, and remains the name under which the standard is marketed. See QSIG for a detailed explanation.


Public Switched Telephone Network. PSTN is an abbreviation used by the ITU-T. PSTN simply refers to the local, long distance and international phone system which we use every day. In some countries it's only one phone company. In countries with competition, e.g. the United States, PSTN refers to the entire interconnected collection of local, long distance and international phone companies, which could be thousands.


  1. Packet Switch Unit.

  2. Power Supply Unit.

Pseudo Cut Through

A switching mechanism where a packet is transmitted from its source port to its destination port only after the first 64 bytes of the packet are in the source port and its destination port is determined.


A pay phone that looks like a real Bell telephone company phone but is owned by a smaller phone company that charges exorbitant fees for long-distance calls.

Psychic ANI

A term created by Howard Bubb from Dialogic to designate what happens when you call someone on one line while they're calling you on the other.


Payload Type: Payload Type is a 3-bit field in the ATM cell header that discriminates between a cell carrying management information or one which is carrying user information.


  1. Portable Teletransaction Computers. These are typically handheld devices used for retail (inventory), healthcare (tracking supplies), mobile field repair (reporting fixes), insurance (visiting car wrecks and other disasters), etc. The devices typically have telecommunications capabilities, sometimes wireless, sometimes landlines. And they typically include microprocessors, memories, displays, keyboards, touchscreens, character recognition software, barcode readers, printers, modems and local and/or wide area data radios.

  2. Personal Telecommunications Center. Infocorp's name for a product most people call a PDA, Personal Digital Assistant.

  3. Pacific Telecommunications Council. A not-for-profit organization open worldwide to anyone or any entity interested in the Pacific hemisphere and involved with telecommunications, broadcasting, informatics, digital media and associated fields. www.ptc.org


Path Terminating Equipment. SONET network elements that multiplex and demultiplex the payload and that process the path overhead necessary to transport the payload. See also Terminating Multiplexers.


An ATM term. Payload Type Indicator: Payload Type Indicator is the Payload Type field value distinguishing the various management cells and user cells. Example: Resource Management cell has PTI=110, end-to-end OAM F5 Flow cell has PTI=101.


Point-To-Multipoint: A main source to many destination connections.


Public Telecommunications Network.


Public Telecommunications or Telephone Operator, first established in the U.K. as part of the British Telecommunications Act of 1981, but now refers to PTOs in all European countries. The PTO has typically evolved from the previous PTT, but other companies have also obtained PTO licenses. A PTO may specialize in certain region or city or may service the entire country.


See Problem Tracking Report.


Presentation Time Stamp: A timestamp that is inserted by the MPEG-2 encoder into the packetized elementary stream to allow the decoder to synchronize different elementary streams (i.e. lip sync).


Public Telecommunications Systems.


An ATM term. PNNI Topology State Element: A collection of PNNI information that is flooded among all logical nodes within a peer group.


An ATM term. PNNI Topology State Packet. A type of PNNI routing packet used to exchange reachability and resource information among ATM switches to ensure that a connection request is routed to the destination along a path that has a high probability of meeting the requested QOS. Typically, PTSPs include bidirectional information about the transit behavior of particular nodes (based on entry and exit ports) and current internal state.


  1. Post Telephone & Telegraph administration. The PTTs, usually controlled by their governments , provide telephone and telecommunications services in most foreign countries. In ITU-T documents, these are the Administrations referred to as Operating Administrations. The term Operating Administrations also refers to "Private Recognized Operating Agencies" which are the private companies that provide communications services in those very few countries that allow private ownership of telecommunications equipment.

  2. Push To Talk. Just as it sounds. A variation on the old walkie talkie. Some cellular telephones now have a features called PTT. You push a button and you can immediately talk with people you've designated ” without having to dial them. For a fuller explanation, see Push To Talk.




Physical Unit. In IBM's SNA, the component that manages and monitors the resources of a node, such as attached links and adjacent link stations. PU types follow the same classification as node types.

PU 2.0 & 2.1

IBM protocols which allow applications written to APCC and interpreted by LU 6.2 to access the mainframe (2.0) and token ring LAN (2.1).

PU Type 2

A physical unit (PU) refers to the management services in SNA node always contains one physical unit (PU), which represents the device and its resources to the network. PU Type 2 is often referred to as a cluster controller.

PU 4

An IBM SNA front end processor.

PU 5

An IBM SNA mainframe, such as a System/370 or System/390. It runs VTAM to handle data communications.

Public Access Terminal

A kiosk (SK series), enclosure (TK series) or a system for special enclosures and custom applications (XE Series) which provides the public access to service. Contains a color monitor and keypad for customer interaction.

Public Announcement Trunk Group

A trunk group used to provide multiple types of announcements, such as the weather, time and sports results.

Public Asynchronous Dial-In Port

A term used in packet switching networks referring to the local phone number of a port into the packet switched network. Some networks provide different numbers for different speeds. Some provide different speeds on the same numbers. See also Private Dial-In Ports.

Public Data Network

A network available to the public for the transmission of data, usually using packet switching under the ITU-T X.25 packet switching protocol. See Packet Switched Network.

Public Dial Up Port

A port on a computer system or on a communications network which is accessible to devices operating over the public switched telephone network.

Public Domain

Imagine you write software. You've just written a great program. You now want to sell it. You have two choices. You can take advertisements, sell it to retailers, get distributors to carry it, hire salespeople, etc. In other words, go the commercial route. This is expensive and requires a major marketing / sales budget. The other choice is to go the Public Domain (also called Shareware) route. This involves giving away your software on various bulletin boards, on many Web sites, in "shareware" direct mail catalogs. In short, putting your software in the public domain. People download the software for free and try it. If they like it, they will send you money. They will do this because you offer them an instruction manual, a new version of the software that doesn't blast "unregistered" on the splash screen when you load the software, or an upgraded version of the software, with more features, or a chit that assuages your guilt at using unpaid-for software that someone (i.e. you) worked real hard on.

Public Exchange

A British word for Central Office. Outside North America, central offices are all called "public exchanges." In the US, a public exchange is typically a local telephone switch. TELECONNECT's phone number in North America is 212-691-8215. The 212 is our area code. The 691 designates the central office or public exchange which serves us. That public exchange belongs to Nynex Company. See also Central Office and CO.

Public Exchange Points

The public exchange points are the major intersections of the Internet. At these exchanges points (MAE-East, MAE-West, PacBell NAP, etc.), the Internet backbones (UUNET, Sprint, etc.) along with hundreds of local and regional Internet access providers, meet to pass Internet transmissions on from one network to another. At these public exchanges points, enormous amounts of data are sent to and from each and every connected network. All of this data is transferred from network to network over the same, common infrastructure. See also NAP and Peering.

Public Key

See Public Key Encryption.

Public Key Encryption

PKE. Also known as asymmetric encryption, and Diffie- Hellman encryption after its inventors (1976), Whitfield Diffie and Martin Hellman. Public Key Encryption is a form of encryption that equips each user with two keys ” a private key and a public key, both of which are provided by a trusted third party known as a Certificate Authority (CA). The public key for each intended recipient, which is known by everyone with access to the key registry maintained by the CA, is used to encrypt the message. The private key, which is known only to the intended recipient and which is kept secret, is used to decrypt the message. Each public key and private key are linked in a manner such that only the public key can be used to encrypt messages to a given recipient, and only the private key held by that recipient can be used to decrypt them. PGP (Pretty Good Privacy) is perhaps the best known example of public key encryption. See also Encryption and PGP.

This longish comes from Netscape. You can read the whole document at http://developer.netscape.com/docs/manuals/security/pkin/contents.htm. Here goes: "All communication over the Internet uses the Transmission Control Protocol/Internet Protocol (TCP/IP). TCP/IP allows information to be sent from one computer to another through a variety of intermediate computers and separate networks before it reaches its destination. The great flexibility of TCP/IP has led to its worldwide acceptance as the basic Internet and intranet communications protocol. At the same time, the fact that TCP/IP allows information to pass through intermediate computers makes it possible for a third party to interfere with communications in these ways:

  1. Eavesdropping. Information remains intact, but its privacy is compromised. For example, someone could learn your credit card number, record a sensitive conversation, or intercept classified information.

  2. Tampering. Information in transit is changed or replaced and then sent on to the recipient. For example, someone could alter an order for goods or change a person's resume.

  3. Impersonation. Information passes to a person who poses as the intended recipient. Impersonation can take two forms:

    1. Spoofing. A person can pretend to be someone else. For example, a person can pretend to have the email address jdoe@mozilla.com, or a computer can identify itself as a site called www.mozilla.com when it is not. This type of impersonation is known as spoofing.

    2. Misrepresentation. A person or organization can misrepresent itself. For example, suppose the site www.mozilla.com pretends to be a furniture store when it is really just a site that takes credit-card payments but never sends any goods.

Normally, users of the many cooperating computers that make up the Internet or other networks don't monitor or interfere with the network traffic that continuously passes through their machines. However, many sensitive personal and business communications over the Internet require precautions that address the threats listed above. Fortunately, a set of well-established techniques and standards known as public-key cryptography make it relatively easy to take such precautions . Public-key cryptography facilitates the following tasks:

Encryption and decryption allow two communicating parties to disguise information they send to each other. The sender encrypts, or scrambles, information before sending it. The receiver decrypts, or unscrambles, the information after receiving it. While in transit, the encrypted information is unintelligible to an intruder. Tamper detection allows the recipient of information to verify that it has not been modified in transit. Any attempt to modify data or substitute a false message for a legitimate one will be detected. Authentication allows the recipient of information to determine its origin ”that is, to confirm the sender's identity. Nonrepudiation prevents the sender of information from claiming at a later date that the information was never sent. The sections that follow introduce the concepts of public-key cryptography that underlie these capabilities.

The most commonly used implementations of public-key encryption are based on algorithms patented by RSA Data Security. Public-key encryption (also called asymmetric encryption) involves a pair of keys ” a public key and a private key ” associated with an entity that needs to authenticate its identity electronically or to sign or encrypt data. Each public key is published, and the corresponding private key is kept secret. Data encrypted with your public key can be decrypted only with your private key. In short, public key encryption uses two keys, a public key (for encrypting messages) and a private key (for decrypting messages). This allows enable users to verify each other's messages without having to securely exchange secret keys. See Encryption and Public Key Infrastucture.

Public Key Infrastructure

PKI. A means by which public keys can be managed on a secure basis for use by widely distributed users or systems. PKI also is known as PKIX, as the IETF's X.509 standard is widely accepted as the basis for such an infrastructure. X.509 defines data formats, key infrastructure components (e.g., security administrators, certificate authorities, users, and directories), and procedures for the distribution of public keys via digital certificates signed by Certificate Authorities (CAs). See also Encryption and Public Key Encryption.

Public Mobile Radio

The European term for what we call Specialized Mobile Radio (SMR) or Trunk Mobile Radio (SMR) in the US. See SMR and TETRA.

Public Network

A network operated by common carriers or telecommunications administrations for the provision of circuit switched, packet switched and leased-line circuits to the public. Compare with private network.

Public Notice

PN. A Public Notice is issued by the Federal Communications Commission (FCC) to notify the public of an action or an upcoming event.

Public Room

A video conferencing center that is arranged with transmission services. Public rooms can be rented by business customers who wish to have a video conference but do not have facility available at their own offices.

Public Safety Answering Point

PSAP. A generic term for the person or group of people who answer 911 emergency phone calls.

Public Service Commission

PSC. The state regulatory authority responsible for communications regulation. Also known as Public Utility Commission, Corporate Commission and in some states, the Railway Commission.

Public Switched Digital Service

PSDS. A generic name for Bell telephone companies' service offerings that provide customer switches the capability of sending data at 56 Kbps over the public circuit switched network. Also known as Switched 56 Kbps Service. See also Switched 56.

Public Switched Network

Any common carrier network that provides circuit switching between public users. The term is usually applied to the public telephone network but it could be applied more generally to other switched networks such as Telex, MCI's Execunet, etc.

Public Switched Telephone Network

Usually refers to the worldwide voice telephone network accessible to all those with telephones and access privileges (i.e. In the U.S., it was formerly called the Bell System network or the AT&T long distance network).

Public Telephone Station

Coin phone. Pay phone.

Public Telephony

A new term to describe what might be possible with a new type of public "phone" which could do more than make and receive analog phone calls. Perhaps it could do videoconferencing? Perhaps it could send faxes? Perhaps it could access remote databases? In short, it could do a bunch of multimedia things. Exactly what hasn't been defined, as yet. Having an RJ-11 plug in it so I could plug my laptop into would be a good beginning, however.

Public Utility Commission

PUC. State body charged with regulating phone companies. Also called Public Service Commissions. See Public Service Commission.


To make information public. These days you can "publish" in many ways ” from paper to CD-ROM to the World Wide Web (i.e. via the Internet).


Making resources available to network users.


See Public Utility Commission.


Personal Unlocking Code. Some cell phones have a PUC-CODE. If you forget your PIN code (and assuming your cellphone has a PIN code), you enter your PUC-CODE and your cellphone will come alive .


A small body of water that draws other small bodies wearing dry shoes into it.

Pull Box

A box with a cover inserted in a long conduit run, particularly at a corner. It makes it easier to pull wire or cable through the conduits .

Pull Tension

The pulling force that can be applied to a cable without effecting specified characteristics for the cable.

Pullcord or Pullwire or Pullstring

A cord or wire placed within a race- way or conduit or ceiling or wall and used to pull wire and cable through.

Pulling Eye

A device on the end of a cable to which a pulling line is attached for pulling cable into conduit or duct liner.

Pulling Glass

Laying fiber-optic cable.

Pulling Strength

Expressed in lbs. The maximum force which may be applied to strength members of a cable. Pulling strength limits are specified for all Belden Fiber Optic cables in the General Line and Fiber Optic catalogs. Affects pulling methods, pulling tension and operation tension.


A type of older telephone twisted-pair cable whose wood-pulp "paper" insulation is formed on the cable during manufacture.

Pulp Cable

Outside telephone cable that uses paper insulation on the twisted coppr pairs. Pulp cable is obsolete technology.


Books and magazines. They are printed on paper, which is made of wood pulp. Despite the popularity of the World Wide Web, CD-ROM, audio tapes and other media, pulpware never has been so popular, for which fact I am ever so grateful. There is nothing quite so nice as curling up in front of the fire with a good book. Books not only are user-friendly, but they just feel good to the touch. The only problem with pulpware is that it is impossible to fix "bugs" once the book is published. There are some " bugs " in this book. Please send email if you find one; I'll fix it with the next edition.


  1. Pulse is the dialing mode for outside lines that is traditionally used by rotary dial telephones.

  2. A quick change in the current or voltage produced in a circuit used to operate an electrical switch or relay or which can be detected by a logic circuit.

Pulse Address Multiple Access

PAMA. The ability of a communication satellite to receive signals from several Earth terminals simultaneously and to amplify, translate, and relay the signals back to Earth, based on the addressing of each station by an assignment of a unique combination of time and frequency slots. This ability may be restricted by allowing only some of the terminals access to the satellite at any given time.

Pulse Amplitude Modulation

PAM. A technique for placing binary information on a carrier to transmit that information. PAM is a technique for analog multiplexing. The amplitude of the information being modulated controls the amplitude of the modulated pulses. Samples of each input voltage are placed between voltage samples from other channels. The cycle is repeated fast enough so the sampling rate of any one channel is more than twice the highest frequency transmitted. See also PAM and PCM.

Pulse Cable

A type of coaxial cable constructed to transmit repeated high voltage pulses without degradation.

Pulse Code Modulation

PCM. The most common and most important method a telephone system in North America can use to sample a voice signal and convert that sample into an equivalent digital code. PCM is a digital modulation method that encodes a Pulse Amplitude Modulated (PAM) signal into a PCM signal. See PCM and T-1.

Pulse Code Modulation Upstream

See V.92.

Pulse Density

Also known as Ones Density. In electrically-based T-Carrier systems, "O"s are represented by zero voltage (i.e., no pulse) and "1"s by alternating positive and negative voltages (pulses). Pulse density refers to the number of no pulse ("O") periods allowed before a pulse ("1") must occur. Typically, no more than 15 no pulse periods ("O"s) are allowed before a pulse ("1") must occur. Pulse density is required by older T- Carrier systems, as repeaters and other network devices rely on it in order to maintain synchronization; some devices also depend on pulse density for power. Not all T-Carrier systems require pulse density; for instance, unchannelized T-Carrier provides clear-channel transmission, without regard for pulse density. See also T-Carrier.

Pulse Density Violation

A pulse density violation occurs if a signal contains more than a specified number of zeros, or the percentage of ones in the signal is less than specified.

Pulse Dialing

One or two types of dialing that uses rotary pulses to generate the telephone number. See Rotary Dial.

Pulse Dispersion

A fiber optic term. Pulse Dispersion is the result of Modal Dispersion. Modal dispersion is an optical phenomenon caused by the dispersion, or spreading out, of the light signals as they propagate through the pure, clear inner core of the optical fiber. Some portions of each light signal travel more or less down the center of the core, while other portions of the signal spread out and strike the edges of the core, at which points they are reflected back into the core by a layer of "cladding," which is glass of a slightly different refractive index. Therefore, portions of the light pulses may take distinctly different paths, or "modes." The portions of the light pulses which dance around the edges of the fiber travel a longer distance than those which travel more directly down the center of the core. Over a long distance from the light source to the light detector, therefore, the pulses can overlap, creating a phenomenon known as "pulse dispersion." The end result is that the light detector may not be able to distinguish between the individual pulses, and the integrity of the data stream is compromised. MultiMode Fiber (MMF) is characterized by an inner core of relatively large diameter and, therefore, is most susceptible to both modal dispersion and pulse dispersion. Single Mode Fiber (SMF) has a thinner inner core, and is less susceptible. See also Dispersion, Fiber, Modal Dispersion, Multi-Mode Fiber, and Single Mode Fiber.

Pulse Distribution Amplifier

DA. A device used to replicate an input timing signal, typically providing 6 outputs, each of which is identical to the input signal. May also perform cable equalization or pulse regeneration.

Pulse Duration Modulation

PDM. That form of modulation in which the duration of the pulse is varied in accordance with some characteristic of the modulating signal.

Pulse Link Repeater

A signaling set that interconnects the E and M leads of two circuits. In E & M signaling, a device that interfaces the signal paths of concatenated trunk circuits. Such a device responds to a ground on the "E" lead of one trunk by applying - 48Vdc to the "M" lead of the connecting trunk, and vice versa. This function is a built-in, switch-selectable option in some commercially available carrier channel units.

Pulse Modulation

A general method of carrying digital information on any system that uses fixed-frequency pulses of transmit information from the source to the destination. Examples are pulse amplitude modulation and pulse duration modulation.

Pulse Overshoot

In T-1, the amount of signal voltage that can remain at the trailing end of a pulse. It can be no more than 10-30% of the pulse amplitude. Also called afterkick.

Pulse Position Modulation

PPM. Pulse position modulation is a variation on frequency modulation. In FM the carrier signal's frequency is modulated by the signal. In Pulse position modulation, instead of a continuous carrier signal, Pulses of constant amplitude are transmitted at different frequencies, the frequency of the pulses being modulated by the transmission.

Pulse Repetition Frequency

PRF. In radar, the number of pulses that occur each second. Not to be confused with transmission frequency which is determined by the rate at which cycles are repeated within the transmitted pulse.

Pulse Stuffing

When timing signals on digital circuits get out of whack, some method of allowing mismatches must be provided. In time division multiplexing, this is called pulse stuffing. One stream of data has bits added to it so its final rate is the same as the master clock.

Pulse To Tone Conversion

Most of the world doesn't have touchtone service. They have rotary, make-and-break phone service and phones. Most computer telephony systems ” from airline timetable audiotext machines to bank balance dispensers ” require the user to punch in touch tone sounds. For people with rotary phones to get access to computer telephony systems, those systems must have a device called a pulse to tone converter ” electronic circuitry which counts the clicks made by a rotary phone and converts them into touch tones. This technology is not 100% accurate and should be accompanied by programming which confirms the input. "You just entered 1034. If that is correct, please say YES or dial 1."

Pulse Train

The resulting electronic impulses that transmit encoded information.

Pulse Width

In T-1, refers to the width (at half amplitude) of the bipolar pulse (typically 324 + or -45 nsec).

Pulse Width Modulation

Another but not very common method of modulating a signal, in which an analog input signal's DC level controls the pulse width of the digital output pulses. See Pulse Code Modulation and Pulse Amplitude Modulation.


The method used for transmitting the phone number dialed to a telephone company switching office.


Product Upgrade Manager.

Pump Laser

An active optical component used in optical amplifiers to amplify and regenerate light signals that lose signal strength over distance ” as all signals do. Pump lasers are lasers that are built into erbium-doped fiber amplifiers (EDFAs) for the purpose of exciting the erbium in the fiber. Pump lasers are actually a type of semiconductor laser about half the size of a AA battery. Pump lasers work by exciting erbium atoms , which then add their energy to optical data signals passing through the fiber and boost the signals' power enough to carry them many miles before needing another boost. See Raman Amplifier. The history of photonics shows improving technology producing increasing distances each year between where amplification/regeneration is needed in long-haul fiber optics transmission systems. See Erbium, Fiber, Laser and Photonics .


To be full of confidence, as in "He's really pumped about his new DSL circuit."


The five worst (i.e. best puns) ever written are:

  1. Two vultures board an airplane, each carrying two dead raccoons. The stewardess looks at them and says, "I'm sorry, gentlemen, only one carrion allowed per passenger."

  2. Two boll weevils grew up in South Carolina. One went to Hollywood and became a famous actor. The other stayed behind in the cotton fields and never amounted to much. The second one, naturally, became known as the lesser of two weevils.

  3. Two Eskimos sitting in a kayak were chilly, but when they lit a fire in the craft, it sank, proving once again you can't have your kayak and heat it, too.

  4. And then there was the Buddhist who refused Novocain during a root canal. He wanted to transcend dental medication .

  5. And finally, There was a man who sent ten different puns to friends , in the hope that at least one of the puns would make them laugh . Unfortunately, no pun in ten did.


  1. The process of perforating a paper tape or card in order to code information into machine readable form.

  2. The process of connecting jumper interconnection wires on a distribution frame. It is called punching because of the tool which places the wire on the metal post of the frame. It is called a PUNCH and requires a heavy "punch" to make it strip its wires, then connect into the Punch-Down Block.

Punch Tool

Punch tools are used to conduct copper wires to terminations, either jacks, blocks or patch panels. They come in two varieties: non-impact and impact. Non-impact tools are less costly, and they push a conductor into its connector. Impact punch tools have a spring mechanism that delivers a jolt of force to the conductor being punched, which helps ensure the cable is properly seated. Impact punch tools are best for most applications. There are different blades for each kind of termination, including the 110 blade, the 66 blade, the five pair 110 blade, the Krone blade and the BIX blade . See Punch Down Tool.

Punch Down

A term used to describe the connection of twisted pair wires to an insulation displacement block. (e.g. a 66 block, or a patch panel). See Punch Down Tool.

Punch Down Tool

A device used to connect twisted pair copper wires to an insulation displacement block (e.g. a 66 block or a patch panel). the punch down tool consists of a slotted blade attached to a heavy-duty plastic handle. Loop the wire between the prongs of an insulation displacement block, slide the slotted blade over the terminal and give the tool a downward push. A spring loaded mechanism in the handle completes the job automatically. The blade spreads the prongs just enough, strips the wire, drives it between the prongs, and neatly cuts the wire with a satisfying "ka chunk." Thus you've produced a perfect "gad tight" termination, which is important since the connection might corrode and the corrosion will insulate the connection. Result: Noise (buzz, hum) on the telephone line and bad voice or data transmission. See Punch Tool.

Punchdown Block

A device used to connect one group of wires to another. Usually each wire can be connected to several other wires in a bus or common arrangement. A 66-type block is the most common type of punchdown block. It was invented by Western Electric. Northern Telecom has one called a Bix block. There are others. These two are probably the most common. A punchdown block is also called a terminating block, a connecting block, a punch-down block, a quick connect block, a cross connect block. A punchdown block will include insulation displacement connections (IDC). In other words, with a connecting block, you don't have to remove the plastic shielding from around your wire conductor before you "punch it down."

Punchdown Tool

A punchdown tool is used to insert cable onto cross-connects, patch panels and jacks. "Punching" a cable means forcing it into an Insulation Displacement Connector (IDC), such as a 66-block. The IDC has replaced Wire Wrap and Solder and Screw Post terminations for connecting conductors to jacks, patch panels and blocks. They pierce the cable jacket to make a connection with the conductor rather than the installer having to strip off the conductor's plastic insulation, saving time. Since IDCs are very small, they can be placed very close together, reducing the size of cross-connects. IDCs are the best termination for high speed data cabling since a gas-tight, uniform connection is made. Most punchdown tools will allow you to install wires on 66-blocks, also known as RJ-21Xs. But there are other IDC blocks. Each of the following types of IDC blocks requires a unique punchdown die for your punch-down tool: (1) 110 Connector; These are very popular connectors for new installations. 110 Patch panels are typically rated Category 5, but always double-check . (2) Krone. Krone cross-connects have a patented 45 degree angled IDC, which typically surpasses standard 66-block and 110 connectors in attainable transmission speed. (3) BIX. BIX IDCs also have superior transmission properties to 66- block and 110 connectors. See Insulation Displacement Connector.

Purchase of Accounts Receivables.


Pure Aloha

A random access technique developed by the University of Hawaii in the early 1970s. In this scheme, a user wishing to transmit does so at will. Collisions are resolved by retransmitting after a random period of time. See also Aloha and Alohanet.

Pure Play

Looking to invest in a company that makes heavy duty storage devices. You might look at EMC, because that's its main business. It's a pure play. You wouldn't look at IBM, though it also make storage devices, because it's not a "pure play" data storage device maker. It makes and sells other things.


Verb. To remove records from a database. To get rid of old voice mail messages.


An imaging term. Purity is the ability of the electron beam to hit precisely the correct phosphor color dot. If a full red page were shown on the display, impurity would result in a purple or greenish color region. This impurity can occur if the shadow mask has been damaged or if the screen has become magnetized. Degaussing the screen may fix the problem.

Purpose Built

A piece of hardware that's built to do one thing and one thing only is often called "purpose built." In short, it's built for one purpose.


There are essentially two ways of getting information from a Web or Intranet site ” push or pull. In the simplest terms, "pull" means that you go into a Web site, and ask for information ” typically by clicking on a button. You will see a page of information. You may ask for a file to be sent (downloaded) to you. This is typically called "pull." You are pulling the information from the web site by doing something ” i.e. clicking away. "Pushing" is a new technology that involves the web site sending you specific material you had only generally asked for. An example, you're surfing the net. You have told one or more sites that you're on line and ready to receive whenever they are ready to send to you. This information might be sent to you as a bar which scrolls along the bottom of your screen ” like the stockmarket quotes that scroll across CNN's financial channels ” or it might be sent to you while your screen saver is on. It might replace your screen saver with live information ” your stocks, news of your favorite baseball teams, etc. According to contemporary wisdom in the Spring of 1997, there are two types of "push" ” Active push and Directed push. Here are two definitions I found of Active and Directed Push: Active: The server on the Web interacts with the client by sending all the content to the client upon the client's request (polling), essentially the way that a client/server application might. PointCast is an example of this. Directed: The server interacts with the push client only occasionally, providing directions (agents, modules, and so on) for how content should be handled or where content is located. The client then gets the information directly from a variety of services and processes it locally. Lanacom Headliner is a good example of this.

Push To Talk

  1. PTT. In landline telephones, cell phones, two-way radio dispatch systems or handheld walkie-talkie systems you often have to push a button to talk and stop pushing to listen. Typically you say "over" or "OK" to indicate it's the other person's turn to talk. In terrestrial radio systems such as SMR (Specialized Mobile Radio), mobile dispatch systems and CB (Citizens Band), push to talk is used where the same frequency channel is employed by for transmit and receive. "Push to talk" was once a symbol of low quality cheap communications. You could only talk in one direction at time. That was a pain. But in early 1990s a cell phone provider called Nextel introduced the "Push to talk" feature on its cell phones. It called the feature "Direct Connect." The feature became wildly popular among groups of people who worked together ” construction workers, electricians, cable TV service technicians, emergency teams, etc. It worked like this: Everyone in the group was given a Nextel "phone number." It didn't look like a normal phone number. It had strange numbers. You put everybody's Nextel strange phone number into the speed dial of your Nextel phone. When you wanted to reach someone in the group, you simply hit the button and started talking. You didn't wait for them to answer and say Hello. Your voice would come out of the speaker on their Nextel phone. If they wanted to reply to your words, they would push their "push to talk" button and you'd hear their reply out of your call phone's speaker, or out of the cell phone's earpiece ” depending on how you set it up. Nextel's cell phone service plans typically allowed unlimited "Direct Connect" calls ” local, long distance, day, night, weekends, etc. With Nextel's Direct Connect you can talk to a group of people simultaneously ” as many as 25. You can also use PTT like instant messaging on computers: Your phone screen can show a list of contacts and indicate who is available to receive a PTT call. Because PTT is often implemented these days on a packet-network, the technologists can design lots of similar customized software and services, like routing specific calls to voice mail or another phone. According to the industry, it's a lot cheaper to embed a cell phone with push to talk abilities than to put in a camera. At one stage, Nextel tried to register the phrase "Push To Talk" as a trademark, claiming they originated the phrase and were the exclusive originators of the phrase. Verizon, for one, thought that was a little over the top and tried to stop them. Actually the term push to talk has been used in the telecom industry since the 1940s. Police radio transmitters of the time used push to talk. As I write this, Verizon and other cell phone companies who were introducing PTT on their cell phones were about to sue Nextel over its trademark claims. See also Citizens Band and SMR.

  2. Push to talk is a protocol which one must observe to conduct a successful voice conversation over some satellite links networks or some IP telephony networks. Much like SMR and CB radio communications, you must wait a brief moment to make sure that your transmission was received and to give the other person an opportunity to respond before you start to talk again; otherwise, you will overtalk the other person, which is known as "clipping." In GEO (Geosynchronous Earth Orbiting) satellite systems, this protocol is necessary due to propagation delay, which is caused by the fact that the communications satellites are roughly 22,300 miles above the equator; even at the speed of light, it takes half a second for the signal to reach the satellite and return to earth. In IP Telephony networks (especially those on Internet) this delay, or latency, is the result of the shared nature of the network ” though the latency is improving as we learn more about QoS ” quality of service.

  3. Push to talk is also a method of payphone operation in which a push button switch is touched by the caller when the called party answers. Once pushed , money in the phone drops into the collection box and the handset microphone is turned on. This system deprives the phone company of revenues for calls to 976 numbers, answering machines or answering services ” for the simple reason that you hear but don't push to talk and pay.

Push Technology

An Internet/WWW (World Wide Web) term describing the reversal of the traditional information gathering paradigm (I hate that word). Instead of seeking out information, information seeks you, based on your demonstrated preferences. Here's how it works: You cruise the Web (Internet or Intranet, seeking certain kinds of information from certain Web sites. You either register your interests or the Web takes note of them. Automatically, you are then presented with notification of changes in that information, as changes take place. You then can access that changed information, or ignore it, as you choose.


Microsoft-speak for a disagreement .

Pushbutton Dialing

Instead of rotary dialing, buttons are pushed to generate the tones needed to place a phone call. Also called Touchtone and Touch-call. Some pushbutton phones do not produce tones, but generate the dial pulses of rotary dials. Some phones and phone systems will generate both rotary dial pulses and tone signaling. See Touchtone.

Pushbutton Dialing To Stations

A special attendant console feature in which the switching system is served by rotary dial central office trunk circuits. A ten-button keyset is provided on the console which allows fast dialing of extension numbers to complete incoming calls.

Pushbutton Originating Register

A register used to store information about originating calls with pushbutton signals.

Pushing the Envelope

The only people not interested in pushing the envelope are postal employers , says comedian, Dennis Miller.


A method of uploading files to a Web server from a HTML-capable (HyperText Markup Language. HTTP (HyperText Transfer Protocol) specifies both POST and PUT. POST performs a permanent action, such as the uploading of an order or the response to a form, or is used which a significant amount of data must be input. POST must be handled by a program or script, which must already exist. PUT can be used to update information on the server, if only a single data item is required. PUT also can be directed at a resource (e.g., program or data element) which does not yet exist. See also HTML and HTTP.


Refers to the packaging of wire and cable. The term itself refers to the packaged product that is ready to be stored or shipped.




  1. Premises Visit Charge.

  2. PolyVinyl Chloride, a common type of plastic used for cladding telephone cable (except that to be run in plenum ceilings). See Plenum Cable.

  3. Permanent Virtual Circuit, a permanent association between two DTEs established by configuration. A PVC uses a fixed logical channel to maintain a permanent association between the DTEs. Once defined and programmed by the carrier into the network routing logic, all data transmitted between any two points across the network follows a pre- deter - mined physical path, making use of a Virtual Circuit. PVCs are widely used in X.25 networks, and are the basis on which communications take place in a Frame Relay network. It is the circuit from end to end in a frame-relay network. See also SVC.


Permanent Virtual Channel Connection: A Virtual Channel Connection (VCC) is an ATM connection where switching is performed on the VPI/VCI fields of each cell. A Permanent VCC is one which is provisioned through some network management function and left up indefinitely.


See Polyvinylidene Diflouride.


Private Virtual Network.

PVP tunneling

Permanent Virtual Path tunneling. Method of linking two private ATM networks across a public network using a virtual path. The public network transparently trunks the entire collection of virtual channels in the virtual path between the two private networks.


Permanent Virtual Path Connection: A Virtual Path Connection (VPC) is an ATM connection where switching is performed on the VPI field only of each cell. A Permanent VPC is one which is provisioned through some network management function and left up indefinitely.


Personal Video Recorder. Also called a digital video recorder. Start with a VCR ” a video cassette recorder which you use for recording TV programs. Substitute the video cassette for a hard disk, add a computer, software and a modem. And you get an intelligent device that can record many hours of TV, that can be programmed to record different programs at different times on different channels. A PVR uses its modem to make a once- every-couple-of-days phone call to "PVR Central" ” a gigantic computer attached to the Internet. The PVR downloads the schedule of TV programs which you can watch on the service you subscribe to ” CATV, satellite TV, etc. And then it chooses which to record ” based on your suggestions or its ideas for what you might like. You can record one episode of a program, or record each playing. For example, you could instruct it to record each time 60 Minutes plays. You could instruct it to record each time tennis comes on ” irrespective of which channel. To my tiny brain, a PVR is one of the most useful consumer gadgets to come along in a long long time.


Printed Wire Board.


PWL means password list file. It's a file Windows uses to store passwords.


Pulse Width Modulation. In communications, encoding information based on variations of the duration of carrier pulses. Also called Pulse Duration Modulation or PDM.




See Personal Wireless Telecommunications.


Pronounced P-times-sixty four. Informal name for the ITU-T family of videoconferencing interoperability standards correctly known as H.261, and addressing codecs and video formats. "P" refers to the value range of 1 through 30, with "Px64" referring to 1 through 30 64Kbps channels for videoconferencing. At a value of 30, the standard address the use of a full E-Carrier facility for video transmission. Px64, or H.261, addresses standards for codecs, as well as video formats. At the upper end, H.261 supports 352 pixels per frame, 288 lines per frame and 30 fps (frames per second). H.261 also addresses much lower levels of capability, offering the advantage of a standard for digital communication between video transmitters and receivers. As a videoconferencing transmitter and receiver go through the process of handshaking, they negotiate the communications protocol, including such issues as compression technique, frame rate, and format. H.261 provides a common standard which disparate devices (not of the same manufacturer) can use for communications. H.261 is part of a family of ITU-T standards known as H.320.


Preboot Execution Environment. See WFM.

Pyramid Configuration

A communications network in which the data link(s) of one or more multiplexers are connected to I/O ports of another multiplexer.

Pyramidal Horn

A wave guide feed horn (i.e. antenna) in which both opposite faces are tapered.

Newton[ap]s Telecom Dictionary
Newton[ap]s Telecom Dictionary
ISBN: 979387345
Year: 2004
Pages: 133

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