Physical Change-Power Line Carrier

Physical Change

The modification of an existing circuit, dedicated access line, or port, at the request of the customer, requiring some physical change or determination.

Physical Channel

A Bluetooth term . A synchronized Bluetooth baseband-compliant RF hoping sequence. Physical link A Baseband level association between two devices established using paging. A physical link comprises a sequence of transmission slots on a physical channel alternating between master and slave transmission slots.

Physical Colocation

An incumbent local exchange carrier (ILEC) provides space within the building housing its central office to other phone companies (e.g. CLECs), to interconnect companies and/or to users to place their equipment. Typically it's done to connect circuits ” transmission or switching ” to the phone company's copper local loops . The interconnector (i.e. the company placing the equipment) installs , maintains, and repairs its own equipment, while the LEC provides power, environmental conditioning, and conduit and riser space for the interconnector's cable. See Colocation.

Physical Connection

The full-duplex physical layer association between adjacent PHYs in an FDDI ring.

Physical Delivery

Delivery of a message in physical form through a Physical Delivery System; for example, delivery of a letter through the U.S. Postal Service. This term is used in X.400.

Physical Delivery Address Component

An X.400 address component that describes how to physically deliver a message. For example, the name and mail stop to hand deliver a message after it is printed. The concept is that the X.400 address would cause a message to be printed on a printer and an individual would complete the hand delivery.

Physical Delivery Office Name

Standard attribute of a Postal O/R (Original/Recipient) Address, in the context of physical delivery, specifying the name of the city, town, etc., where the physical delivery is to be accomplished. An X.400 term.

Physical Delivery Office Number

Standard attribute in a Postal O/R (Originator/Recipient) Address that distinguishes between more than one physical delivery office within a city, etc. An X.400 term.

Physical Delivery Organization Name

A free form name of the addressed entity in the postal address, taking into account the specified limitations in length. An X.400 term.

Physical Delivery Personal Name

In a postal address a free form name of the addressed individual containing the family name and optionally the given name(s), the initial(s), title(s) and generation qualifier, taking into account the specified limitations in length. An X.400 term.

Physical Delivery Service

The service provided by a Physical Delivery System. An X.400 term.

Physical Delivery Service Name

Standard attribute of a Postal O/R (Original/Recipient) Address in the form of the name of the service in the country electronically receiving the message on behalf of the physical delivery service. An X.400 term.

Physical Formatting

The second step in structuring a hard drive so that you may write to it. Physical formatting follows partitioning.

Physical Interface Card

PIC. An intelligent line card that provides a high-speed and secure processing capability beyond the typical connectivity of first generation router cards. This robust line card basically connects a communications channel or circuit to multiport switching equipment. This term is used by Riverstone Networks and Juniper Networks and will most likely pick up popularity when competitors like Cisco also adopt PIC as a more robust term than Network Interface Card (NIC) or line card.

Physical Layer

1. The OSI model defines Layer 1 as the Physical Layer and as including all electrical and mechanical aspects relating to the connection of a device to a transmission medium, such as the connection of a workstation to a LAN. Included at this layer are issues specific to the manner in which a device gains physical access to the medium and how it goes about putting bits on the wire or extracting bits from the wire. As the lowest level of network processing, below the Link Layer, the Physical Layer deals with issues such as volts , amps, and pin configurations and handshaking procedures. Communications hardware (e.g., NICs and MAUs) and software drivers are specified at the Physical Layer.

2. The ATM Physical Layer (PHY) loosely corresponds with the OSI version. In the ATM world, Physical Layer functionality is discussed in terms of the Physical Medium sublayer (PM) and the Transmission Convergence (TC) sublayer. The implementation of the ATM Physical Layer is addressed in the ATM Forum's UNI ( User Network Interface) specifications.

Physical Layer Connection

An association established by the PHY (OSI Physical Layer) between two or more ATM entities. A PHY connection consists of the concatenation of PHY links in order to provide an end-to-end transfer capability to PHY SAPs.

Physical Layer Medium Dependent

The Physical Layer sublayer that defines the media dependent portion of the Physical Layer in FDDI. Items defined by PMD include transmit and receive power levels, connector requirements, and fiber optic cable requirements.

Physical Layer Protocol

The Physical Layer sublayer that defines the media independent portion of the Physical Layer in FDDI. Items defined by the PMD include transmit and receive power levels, connector requirements, and fiber optic cable requirements.

Physical Link

A real link which attaches two switching systems.

Physical Markup Language

PML. An Auto-ID Center-designed method of describing products in a way computers can understand. PML is based on the widely accepted eXtensible Markup Language used to share data over the Internet in a format all computers can use.

Physical Media

Any means in the world for transferring signals between OSI systems. Considered to be outside the OSI Model, and therefore sometimes referred to as "Layer O." The physical connector to the media can be considered as defining the bottom interface of the Physical Layer, i.e. Layer 1 of the OSI Reference Model.

Physical Medium

PM. In ATM terms, the Physical Medium sublayer is the dimension of the Physical Layer (PHY) which specifies the physical and electrical/optical interfaces with the physical media. See also Physical Layer and Transmission Convergence.

Physical Rendition

The transformation of an MHS (Message Handling System) message to a physical message (e.g., by printing the message on paper and enclosing it in a paper envelope). An X.400 term.

Physical Security

Ways to stop someone from gaining physical access to your stuff. Methods include locks, security personnel and guard dogs.

Physical Signaling Sublayer

PLS. In a LAN or MAN system, that portion of the OSI Physical Layer that interfaces with the medium access control sublayer and performs bit symbol encoding and transmission, bit symbol reception and decoding, and optional isolation functions.

Physical Slots

Slots that are available to cards in a card shelf.

Physical Topology

The actual arrangement of cables and hardware that comprise a network. In other words, the actual physical appearance of a network. Typical physical topologies in the LAN world, for instance, include Bus, Ring and Star. The Physical Topology may differ significantly from the Logical Topology.

Physical Unit

PU. 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.

Physical Unit Control Point

PUCP. In SNA, the component that provides a subset of the system-services control point (SSCP) within a node. Types 1, 2 and 4 nodes contain a PUCP, while a Type 5 (host) contains a SSCP.

PHz

Petahertz (10 to the 15th power hertz). See also Spectrum Designation of Frequency.

PI

1. See Power Influence.

2. Presentation Indicator. A two-bit field in the Calling Party Number (CPN) subfield of the Initial Address Message (IAM). In an ISDN network, the IAM is part of the call set-up protocol. The PI indicates to the terminating switch whether it should pass to the called party the telephone number of the calling party, which telephone number is contained in the CPN. See also CPN, IAM, and ISDN.

3. pi. The constant equal to the ratio of the circumference of a circle to its diameter, which is approximately 3.141593.

PIA

Personal Information Appliance. A name for a product most people call a Personal Digital Assistant (PDA).

PIAFS

PIAFS is a V.110-like protocol for use over PHS, a digital cell phone network found in Japan.

PIC

1. See Primary Interexchange Carrier.

2. Plastic Insulated Conductor. A metallic cabling system in which the individual conductors are covered with an extruded coating of plastic. Virtually all cabling systems fall into this category. See also Icky PIC.

3. Also an imaging term. Picture Image Compression. Intel-DVI Technology's on-line still image compression algorithm. See DVI.

4. Personal Intelligent Communicator. A General Magic term for a product most other people called a Personal Digital Assistant. See PDA.

5. Point In Call. See Basic Call State Model.

6. Programmable Interrupt Controller. A chip or device that prioritizes interrupt requests generated by keyboards, serial ports, and other devices and passes them on to the CPU in PC in order of highest priority. See also IRQ.

PIC CARE

Primary Interexchange Carrier Customer Account Record Exchange. PIC CARE records are exchanged between the LEC (Local Exchange Carrier) and the IXC (Interexchange Carrier) at the time an account is provisioned. PIC CARE information includes the identity of the IXC, and the type of customer line (e.g., residential line, business line, or PBX trunk) in use. PIC CARE records also contain a "jurisdiction field" which identifies the kind of long distance calls (i.e.; only interLATA; interLATA and/or international; or interLATA, intraLATA and international) carried by the IXC for the customer.

PIC Freeze

Pre-subscribed Interexchange Carrier Freeze. A PIC Freeze is when a customer tells his local phone company (LEC ” Local Exchange Carrier) that nobody is allowed to change his preference on which long distance company he will use. A PIC free is designed to prevent which is unauthorized changing of your long distance telephone carrier. See also PICC, Jamming and Slamming.

Picasso Porn

The semi-scrambled transmissions from adult cable channels that can sometimes be seen and heard by nonsubscribers. This definition courtesy Wired Magazine. According to Ray Horak, my Contributing Editor, the scrambling technique used by CATV operators over analog coaxial cable systems (which they mostly are) simply involves "twisting" the audio and video frequencies; thereby, you are able to hear and view the adult channel only if you have paid for the service and, therefore, have a converter box that can unscramble the signal. However, and according to Ray, you'll notice that the picture comes in clear when the actors stop moaning and the obnoxious music stops.

PICC

Primary Interexchange Carrier Charge, also known as Pre-subscribed Interexchange Carrier Charge. The FCC- mandated (May 1997) flat-rate charge which applies to pre-subscribed IXCs connecting to the end user through LEC facilities. The PICC applies first to primary lines; to the extent that PICC charges, in combination with the SLC (Subscriber Line Charge) and the monthly tariff line charge, are insufficient to provide the LEC with full recovery of the costs of the local loop, a lower PICC also may apply to non-primary (i.e., secondary) residential lines and multi-line business lines. The PICC became effective in 1998, and can either increase or decrease over time. While the LEC bills the end user directly for the SLC, it bills the IXC for the PICC. The IXCs are free to recover the PICC from end users; AT&T, for instance, has imposed a Carrier Line Charge on its end users in order to recover this cost. This charge was partly eliminated in May 2000 by the FCC. See CALLS Proposal. See also Access Charge and SLC.

Pick

The computer operating system of Pick Systems, Inc. Pick is a neat operating system that has only caught on in a very small way. Steve Lamb of Peet's Coffee & Tea, Inc. wrote me, "Those of us who have actually become familiar with it really do love it, and the Pick community, though small, is very much a family-like group . We occasionally ponder the question of what would have happened if Pick Systems had had the same marketing approach as someone like IBM or Microsoft." www.picksys.com.

Pick-And-Place

The manufacturing operation in which components are selected and placed in the correct position on a substrate for the purpose of interconnection to the substrate.

This is most commonly done with a programmable machine equipped with a robot arm.

Pick cable

Outside telephone cable with plastic insulated pairs.

PICMG

PCI Industrial Computer Manufacturers Group. An international consortium of vendors of industrial computer products, PICMG was formed to develop specifications for PCI (Peripheral Component Interconnect) based systems and boards for use in industrial and telecommunications computing applications. The electrical and mechanical specifications of PICMG enable CPU boards and backplanes from different manufacturers of industrial-grade computers to be interchangeable. PICMG specifications include CompactPCI, rackmount applications and PCI for passive backplane, standard format cards. See CompactPCI and PCI. www.picmg.org

Pickup

Means you can answer a call from your phone. There all sorts of "pickups." The most common is GROUP PICKUP. Here you are part of a group and you can answer ” from your phone ” the call of anybody in that group, usually by punching a digit or a button or two. There's also NIGHT PICKUP, which typically allows anyone to answer an incoming call after hours, again by punching down a digit or a button or two. In TELECONNECT Magazine, we have one GROUP PICKUP. Everybody in the company belongs to that Group and everyone can answer everyone else's phone. We believe this simplifies things. It also allows anyone, anywhere , from any phone, to play telephone attendant, answering any and all incoming calls and transferring them through the system.

Pickup Group

Imagine you're on a phone behind a PBX. Imagine you work in accounting, a group of five people. You can program most PBXs such that a call to your phone could be answered by anyone else in your group, and vice versa, you could answer someone else's ringing phone in your group. When you set your PBX up, you need to program which Pickup Groups which phones belong in.

Pickup Pattern

A determination of the directions from which a microphone is sensitive to sound waves. It varies with the mike element and mike design. The two most common pickup patterns are omni- and uni-directional.

Pico

Prefix meaning one-trillionth, or one-millionth of a millionth. A pico is ten to the minus 12. See Atto, Femto and Nanosecond.

Picocell

A wireless base station with extremely low output power designed to cover an extremely small area, such as one floor of an office building.

Picofarad

One-trillionth of a farad. A unit of capacitance usually used to designate capacitance unbalance between pairs and capacitance unbalance of the two wires of a pair to ground.

Piconet

A Bluetooth term. A collection of devices connected via Bluetooth technology in an ad hoc fashion. A piconet starts with two connected devices, such as a portable PC and cellular phone, and may grow to eight connected devices. All Bluetooth devices are peer units and have identical implementations . However, when establishing a piconet, one unit will act as a master and the other(s) as slave(s) for the duration of the piconet connection. All devices hare the same physical channel defined by the master device parameters (clock and BD_ADDR). Here's another explanation: a piconet is a collection of devices connected in an ad hoc fashion via Bluetooth RF (Radio Frequency) technology. The connection may begin with any two devices, such as a wireless PC and a cellular telephone, and may grow to as many as eight devices, including PDAs (Personal Digital Assistants) and anything else you might imagine. While all piconet devices are peers (i.e., equals) in terms of connectivity, one device acts as the master, and the others as slaves, for the duration of the piconet connection. A scatternet is formed when multiple, non-synchronized piconets are linked. See also Bluetooth and Pico.

Picosecond

One-millionth of a millionth of a second. A picosecond is ten to the minus 12 of a second. One picosecond ” a trillionth of a second ” is a spot of time from the domain of molecules. Light, traveling for one picosecond, would barely make it across the period at the end of this sentence . Only with a laser that generates picosecond light pulses can scientists freeze the short-duration motion of molecules and produce images of what goes on at the molecular level. Used in this way, the picosecond laser is comparable to a strobe, which can freeze the motion of a sprinter's stride in time-lapse photography. See Nanosecond.

PICS

1. Protocol Implementation Conformance Statement: A statement made by the supplier of an implementation or system stating which capabilities have been implemented for a given protocol.

2. Product Inventory Control System.

3. Plug-In Inventory Control System. Plug-In's are circuit cards which fit into central office equipment and which control various aspects of transmission and carrier circuit functionality and usage. See also PICS/DCPR.

4. A Macintosh-specific "multimedia" format for exchanging animation sequences (developed in 1988 by Macromind and others). PICS assembles several PICT files ( frames ) and combines them into one file.

PICS/DCPR

The Plug-in Inventory Control System/Detailed Continuing Property Records (PICS/DCPR) system maintains records of plug-in equipment. It is an OSS (Operations Support System) that was developed many years ago by the Bell System. PICS/DCPR interfaces with TIRKS (Trunks Integrated Records Keeping System) in the circuit-provisioning process. PICS/DCPR and TIRKS are still used by the RBOCs. See also TIRKS.

PICT

Picture Format. Developed by Apple in 1984 as the standard format for storing and exchanging files. PICT2 (1987) supports eight-bit color and gray scale. The PICT format now is widely used among Macintosh graphics and page-layout applications as an intermediary file format for transferring files between applications. The PICT format supports RGB files with a single alpha channel, and indexed-colour, grayscale, and bitmap files without alpha channels. The PICT format is especially effective at compressing images with large areas of solid colour."

Picture Element

See Pixel.

Picturephone

AT&T's trademark for a video telephone that permitted the user to see as well as talk with the person at the distant end. AT&T introduced it at the 1964 World's Fair in Flushing Meadow, Queens, New York City. The device had a camera mounted on the top and a 5.25" x 4.75" screen. Audio signals were transmitted separately from video signals and the system could not use the public switched telephone network. It needed a transmission bandwidth of 6.3 Mbps and no one wanted to pay the price for the service. It never got off the ground. AT&T picked up on the name Picturephone and came out with an offering called Picturephone Meeting Service which provided full video teleconferencing. It was available through rented rooms or through equipment sold or rented to corporations. It also didn't do too well since the service was expensive and no one wanted to spend the time traveling to the few and far between conferencing room. AT&T has abandoned Picturephone, the product, and has closed down the Picturephone Meeting Service rooms it rented to corporations.

Picturephone Meeting Service

An AT&T service once provided under experimental tariff. It combined TV techniques with voice transmission. PMS is usually only available between telephone company-located picturephone centers. Most (we think all) have now been closed down. The venture was losing too much money.

PID

Protocol Identifier. A field in the Call User Data included in the Call Request Packet sent to the ISP host for POS terminal initiated calls.

PIECE

Productivity, Information, Education, Creativity, Entertainment. Microsoft's trick for remembering the big five multimedia computing applications.

Piepser

The German word for beeper. Also the name of a small beeper made by Swatch and sold by BellSouth.

Piesio

The Greek prefix meaning near.

Piezo-Electric Crystal

A type of crystal which, when subjected to mechanical stress, generates current; or which, when subjected to varying electrical stresses, generates mechanical movement. Most familiar type is Rochelle Salts crystal. An old radio term.

PIF

1. Personal Communications Services Industry Forum.

2. Program Information File, a binary file, which contains information about how Windows should run an MS-DOS application, such as how much memory it needs, the path to the executable file, and whether the window in which the program is run closes automatically when the program terminates.

3. Public Inspection File. A set of documents which must be maintained by every cable television system at a convenient location in the cable community: at the system's office, or at some other convenient location such as an attorney's office or the local public library. The contents of the PIF are specified in Sections 76.302 and 75.305 of the FCC Rules. Any member of the public:

   • Has the right to see the PIF on request.

   • Has the right to request accommodations where the PIF can be reviewed without disturbance.

   • Has the right to request photocopies of any or all documents in the file at a reasonable cost.

The Public Inspection File should be kept separate from all other files, both physically and operationally. This will reduce the chance of inadvertently releasing to the public any information which is not specifically required.

Pig

Coin banks are often shaped like pigs. Why? Long ago, dishes and cookware in Europe were made of a dense, orange clay called "pygg". When people saved coins in jars made of this clay, the jars became known as "pygg banks." When an English potter misunderstood the word, he made a bank that resembled a pig. And it caught on.

Piggyback Attack

Form of active wiretapping in which the attacker gains access to a system via intervals of inactivity in another user's legitimate communication connection. Sometimes called a "between-the-lines" attack.

Piggy Back Data Slurp

Imagine a data communications connection between two distant computers. Somewhere along the line, someone has attached a terminal or communicating computer and begun to capture the data as it flows across the line. In short, someone had slurped out data on a piggyback terminal or communicating computer. A piggyback data slurp could continue forever, without either party being aware their data and their conversations were being stolen ” so long as the piggyback terminal didn't let its presence be known. The piggyback terminal, however, may insert itself into the conversation, pretending to send back authentic communications, thus misleading one or both of the parties. You could call this active deception or proactive espionage.

Piggyback

A cellular term. A microcell sometimes "piggybacks" on a larger macro- cell, depending on the macrocell for some of its operational intelligence. In other words, the microcell acts as a semi-intelligent remote, relying on the more intelligent, centralized macrocell for higher-level intelligence to control its more complex operations.

Piggyback Board

Another name for a daughterboard on a card inside a PC.

Piggybacking

A technique used at the data link or transport layer in a layered network architecture that allows for transmission acknowledgments to be carried in transmission frames received from the destination.

Pigtail

1. Multiple pieces of short cable with single circuit connectors connected to a multi-conductor cable. See Octopus.

2. A short, permanently attached piece of optical fiber used to link the transmitter and receiver to the transmission fiber.

Pigtail Antenna

The standard cellular antenna for a car. The term "pigtail" refers to the spring-like section in the lower third of the antenna, the phasing coil.

Pilot Error

See Cockpit Problem.

Pilot Installation

A small installation that may precede a large, expensive planned installation, used to show the benefits in order to get a customer's commitment for a larger installation, or to identify and solve problems before installing an enterprise- wide system.

Pilot Number

Identifies a Hunt Group or Distribution Group. See also Distribution Group.

Pilot-Make-Busy Circuit

A circuit arrangement by which trunks provided over a carrier system are made busy to the switching equipment in the event of carrier system failure, or during a fade of the radio system.

PIM

1. Protocol Independent Multicast. Multicasting is the process of sending one packet to many people without having to duplicate the packet at the source for each recipient. Multicast is often used for multimedia transmissions such as streaming video or sound. Many multicast routing protocols like Distance Vector Multicast Routing Protocol (DVMRP) and Multicast Extensions to OSPF (MOSPF) were designed for a network where bandwidth is plentiful and all the multicast subscribers are in the same region of the network. However, networks in the real world have a wide variety of configurations, and more often than not, multicast subscribers are scattered across the network in small groups with a limited amount of available network resources. Since most multicast routing protocols were created based on assumed ideal network conditions, they are often inefficient with network bandwidth and resources. Protocol Independent Multicast (PIM), however, makes better use of network bandwidth and adapts to network conditions and subscriber distribution for optimized multicast session performance. PIM follows standard multicast protocol procedures and uses discovery techniques to find the optimal multicast path between the multicast server and the subscribers. PIM is also very scalable, so it operates on small or very large networks. Since it doesn't rely on any single unicast routing protocol, it operates over any layer-2 network configuration. Because PIM was designed to be a simple, effective protocol, it lacks the sophistication of more complex routing protocols like DVMRP and MOSPF. PIM has to perform more operations to accomplish the same task, which results in an increased load for router processors and packet duplication. However, when compared to other protocols, PIM is an advance in multicast technologies. PIM has two distinct modes to handle varying network conditions: First, PIM sparse mode (PIM-SM) and second, PIM dense mode. (PIM-DM) Sparse mode assumes that the multicast subscribers are far apart, are not grouped together, or have limited bandwidth, while dense mode assumes subscribers are close together on the network and have plenty of bandwidth for the transmissions. In each situation PIM uses the mode best suited to optimize its performance based on the configuration of the subscribers of the multicast stream. See also Multicast.

2. Personal Information Manager. A specialized form of software used by individuals and groups for keeping track of contacts (including addresses and phone numbers ), appointments, project schedules, to-do lists, reminder notes, anniversaries, etc. PIMs are also called contact managers. Contemporary PIMs also are e-mail clients that allow such information to be shared with friends and coworkers. PIMs may be Web-based, as is the case with My Personal Diary from Lycos. Examples of PIMs include Maximizer, My Personal Diary (Lycos), TeleMagic, Organizer (Lotus), Outlook (Microsoft), and SideKick (Borland).

3. Plug In ISDN Module. A module in the form of a printed circuit board (PCB) that plugs into a data switch or router to make it ISDN-compatible.

4. Presence and Instant Messaging.

PIM Dense Mode

PIM DM. Protocol Independent Multicast Dense Mode. A multicast protocol similar to DVMRP in that it uses Reverse Path Forwarding but does not require any particular unicast protocol. See Protocol Independent Multicast Dense Mode for a longer explanation.

PIM Sparse Mode

A multicast protocol that works by defining a rendezvous point that is common to both sender and receiver. Sender and receiver initiate communication at the rendezvous point, and when flow begins it occurs over an optimized path. See PIM for a longer explanation.

PiMF

Pairs in Metal Foil. See SSTP.

PIN

1. Procedure Interrupt Negative. A fax term.

2. Photo INtrinsic diode. Also known as PIN Diode. A type of photodetector used to sense lightwave energy and then to convert it into electrical signals. PINs are matched with LEDs (Light Emitting Diodes) in fiber optic transmission systems of relatively low capacity (i.e., less than 500 Mbps for); currently, such systems are deployed for interconnection of hubs, switches and routers in a LAN environment. See also LED. See APD and Laser Diode for descriptions of the components used in high-bandwidth fiber optic systems.

3. Personal Identification Number. A code used by a mobile telephone subscriber in conjunction with a SIM card to complete a call. A code used by a credit card user. A code used by an ATM card user, etc. In short, a code to protect you against fraud. A code that you remember, which you don't write down anywhere and which theoretically can't fall into the wrong hands.

4. A Bluetooth term. Personal Identification Number. The Bluetooth PIN is used to authenticate two devices that have not previously exchanged link key. By exchanging a PIN, the devices create a trusted relationship. The PIN is used in the pairing procedure to generate the initial link that is used for further identification. See also Piconet.

PIN Code

Personal Identity Number code. A code used by a mobile telephone subscriber in conjunction with a SIM card to complete a call. See PIN.

Pin Diode

A photodiode made with an intrinsic layer of undoped material between doped P and N layers and used as a lightwave detector.

PIN Number

Personal Identification Number. A group of characters entered as a secret code to gain access to a computer system, such as the one that completes long distance calls. See Personal Identification Number.

Pin Photodiode

An optical detector that converts light into electricity. This type is the typical diode used in a fiber optic receiver.

PIN(BB)

A Bluetooth term. The PIN used on the baseband level. The PIN(BB) is used by the baseband mechanism for calculating the initialization key during the paring procedure. (128 bits)

PIN(UI)

A Bluetooth term. The PIN used on the user interface level. The PIN(UI) is the character representation of the PIN that is entered on the UI level.

Pincushion Distortion

When a video screen is distorted ” with the top, bottom and sides pushing in ” the screen is said to be suffering pincushion distortion.

Pine

Program for Internet News and Email. Pine was developed at the University of Washington (there are lots of pine trees in Washington state) as an easy to use, character-based e-mail client for use with UNIX and MS-DOS host computers. Pine was based on an older e-mail program call Elm (there also are lots of elm trees in Washington state), but since has evolved well beyond those simple origins. Pine sometimes is decoded as "Pine Is No longer Elm."

Ping

1. To ping a computer basically means that you send out a small amount of information, or packet, to another computer connected over a network ” the Internet or a private network or both. Then you wait for a response from the other computer. If you get a response, you know the computer exists and your network is working. Ping is a actually a software program written by Mike Muuss to test whether a particular network destination on the Internet is online (i.e., working) by bouncing a "signal" off a specified IP destination address. Every PC these days comes with ping software. Pinging is among the more useful tools I have on my computer. It allows me to pinpoint when something is wrong with my network. Let's say I'm at home and I can't get to www.Microsoft.com. Whose fault is it? The first thing I'll do is to go into MS-DOS and ping 10.1.25.1. (That's not the real number, but it's close.) If I get a response, that means my firewall is working. Then I ping the server of my local DSL provider (called Prism), which is 199.105.128.148. If I get a response, I then ping 199.105.128.1, which gets me just out of their system. If I get a response, I then ping globix.com, whose server is in my town, New York City. At some point I won't get a response. At that point, I know which part of my system or which part of Prism or which part of the Internet is down (or I know they're using a firewall, which is programmed not to respond). Try it yourself. Go to DOS from Windows. Then type ping microsoft.com. Neat. Notice how it tells you how long it takes.

   According to Mr. Muuss, the name "ping" refers to the sound of a SONAR return. It seems as though Mr. Muuss had done a good deal of college work on the modeling of SONAR and RADAR systems, both of which are based on the concept of transmitting a signal, and seeing how long it takes that signal to complete a round trip from the transmitter to the target device and back. Some years later, Mr. David Mills apparently made an acronym out of "ping;" according to his definition, "PING" means "Packet InterNet Groper." PING is an example of a backronym, a word that often is interpreted as an acronym, although it was not so intended.

   In any event, the ping utility makes use of ICMP (Internet Control Message Protocol) packets. The pinging device sends ICMP Echo Request Packets to one or more target IP (Internet Protocol) addresses. If the target address is active, it has a working IP protocol stack and is online (i.e., turned on, and networked). Assuming that is so, the target device will return an ICMP Echo Reply Packet. As the IP header contains a Time-To-Live (TTL) counter which is decremented by timers in the intermediate switches and routers, the time of the round-trip signal can be calculated, which yields some information about the performance level that can be expected for a client/server application across a network. If no ICMP packet is returned, the target device is either down or unreachable, or the performance of the networked application is so slow that the packets "timed out" and "died" before they could be accepted and returned. The term is often used as verb: "Ping host X to see if it is up!" Ping is useful for testing and debugging networks. By the way, you can ping your very own PC. Ping 127.0.0.1. See also Acronym.

2. A graphics file format ending in .png, which was developed to overcome deficiencies of .gif and .jpeg file formats, which are commonly used on the Web. Ping allows 16-, 24- , and 32-bit images, providing for better color depth. The downside is that higher-quality images require more storage and involve longer download times.

Ping of Death

The Ping of Death is a denial-of-service attack that crashes servers by sending invalid IP ping packets. The first version, discovered in early 1997, affected mostly Macintosh and Unix servers, not NT servers. The problem faded after vendors posted patches to their servers, and Microsoft posted a new PING.EXE file that prevented users from generating the invalid pings . The resurrected Ping of Death, however, takes a slightly different approach: According to PC Week, it modifies the header of the ping to indicate that there is more data in the packet than there actually is. "Effectively, the server hangs because the IP stack is waiting for the rest of the data," said Mike Nash, Microsoft's director of server marketing in 1997.

Ping Pong

1. A method of getting full duplex data transmission over a two wire circuit by rapidly alternating the transmission direction. See Ping Ponging.

2. A disruptive phenomenon that occurs in digital cellular networks when the cell phone repeatedly reselects two cell sites of approximately equal strength. This problem is overcome through the use of a buffer area known as a "hysteresis."

3. A disruptive phenomenon that occurs in digital cellular networks when both transmission and reception take place over the same frequency channel, although in separate time slots. This problem is overcome through the use of separate frequency channels.

Ping Ponging

Routing that causes a packet to bounce back and forth between two modes. See Ping Pong.

Pink

Adult audiotext, i.e. dirty talking over the phone for money.

Pink Flamingos

See Flamingos, Pink.

Pink Noise

Noise in which power distribution is logarithmic through the spectrum, with an equal amount of power in each octave.

Pink Pages

In Australia, at one stage, the list of businesses organized by industry, were printed on pink paper and called the Pink Pages. They are the equivalent of the North American "Yellow Pages."

Pinouts

Pin configurations for cabling. In other words, which pin connects to which cable. Not all pins are always connected. Not all cables always connected.

Pinosecond

One-trillionth of a second. One-millionth of a microsecond.

PINT

PSTN and Internet Internetworking. The PINT WG (Working Group) of the IETF (Internet Engineering Task Force) addresses connection arrangements through which Internet applications can request and enrich PSTN (Public Switched Telephone Network) services. For example, PINT might include a Web-based Yellow Pages service, with the ability to launch a return call via the conventional PSTN based on a Web search-and-click process. In this example, the Internet, or other IP-based network, might be used to request the placement of the call, and the PSTN would execute the call. The call might be a return call (either voice or fax) from a call center with a Website, which might include a commercial vendor that might be requested to return a call regarding a product question or service issue, or a governmental agency such as a weather bureau that might be requested to call in the event of a serious weather alert. See also IETF, IP, and PSTN.

Pip Tone

The tone that notifies you of a call waiting, assuming you subscribe to "call waiting." See Call Waiting.

Pipe

1. A communications process within the operating system that acts as an interface between a computer's devices (keyboard, disk drives , memory, and so on) and an applications program. A pipe simplifies the development of application programs by "buffering" a program from the intricacies of the hardware or the software that controls the hardware; the application developer writes code to a single pipe, not to several individual devices. A pipe is also used for program-to-program communications and can be a connection between two processes so that the output from one immediately becomes the input for the other. Indicated by the character.

2. A transmission facility. Pipe usually is used when discussing transmission bandwidth. For instance, fiber optics is a "big pipe," because it offers lots of bandwidth. See also Bandwidth.

3. Private Investment in Public Equities. When public companies become cheaper than private companies, some venture capital firms often invest in public companies. This is valled PIPE.

Pipe Mount

A mounting system used for mounting an antenna mast to a vent pipe on a roof.

Pipelining

1. Executing instructions by breaking them into component parts and processing them in parallel on separate processors. This reduces reduce cycle time and increases the computer's performance.

2. In imaging, pipelining also lets an imaging card start compressing and writing the image to disk while it is still being scanned.

3. In networking, pipelining is a technique used at the transport layer or data link layer in a layered network architecture that allows for the transmission of multiple frames without waiting to see if they are acknowledged on an individual basis. Each frame may have to be acknowledged later and in sequence, or a process of implied acknowledgment may be employed. Implied acknowledgment is a process whereby negative acknowledgment of a specific frame implies that all previously transmitted frames have been received correctly.

PIR

1. Peak Information Rate. This word is used in context of an Ethernet interface to specify its performance in terms of peak number of frames transmitted per second.

2. Passive Infra-Red.

Piracy

Any impersonation, unauthorized browsing, falsification or theft of data or disruption of service or control information in a network.

PISD

Planned In-Service Date. The date the your vendor quotes for installation of a new system or circuit. A due date, in other words. I think that if your vendor missed the PISD, you would be "PISD off."

PITA

Abbreviation for "Pain In The Ass;" commonly used on E-mail and BBSs (Bulletin Board Systems).

Pitch Control

Variable control for increasing or decreasing the speed of a tape deck or turntable.

PIU

1. Path Information Unit in SNA.

2. See Percent of Interstate Usage.

PIX

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

Pixel

PIcture ELement. The smallest unit of area of a video screen image that can be turned on or off, or varied in intensity. The single point on a CRT display. The single point in a facsimile transmission. The image you see on your screen is the result of some pixels being on and others off. A pixel is the smallest part of the video screen that can be turned on or off or varied in intensity. It is one of the phosphor elements that coat the inside of a CRT tube. Pixels glow when struck by an electron beam. The number of pixels in the most common computer screen, a VGA monitor, is 640 x 480, with the first number (640) being the number of pixels in each horizontal row and the second number (480) the number of rows displayed. VGA stands for Video Graphics Array. Resolution (crispness and clarity of text and images) improves as the number of pixels displayed increases. If it's a color screen, a pixel is really three dots together, or clusters of red, green and blue ” the triad of colors that, when energized, add up to white, or when the set is turned off, show as black. The phrase "picture element" was first used in 1927 in the magazine "Wireless World" writing about the mosaic of dots, or picture elements. See PEL.

Pixel Shim

A small, usually invisible graphic used in an HTML document to create a page format. "I had to use a pixel shim to get the type to space correctly." A Wired Magazine term.

Pixilation

A technique used by cinematographers and stage managers to make human performers appear to move as it artificially animated. Using a stop-frame camera, the pixilator can distort and speed up the motion of actors.

PIXIT

Protocol Implementation eXtra Information for Testing: A statement made by a supplier or implementor of an IUT (Implementation Under Testing) which contains information about the IUT and its testing environment which will enable a test laboratory to run an appropriate test suite against the IUT.

Pixrects

Pixrects is the primary graphics programming interface in the SunView Window System from Sun Microsystems. It is replaced in the OpenWindows XView toolkit by the Pixwin interface, which is a thin layer on top of Xlib.

Pixwin

Pixwin is the primary graphics programming interface in the XView toolkit from Sun Microsystems. Pixwin is a thin layer on top of Xlib.

Pizza Box

A wireless term referring to a phased array antenna. The device is small, square, and flat, resembling a pizza box. If you open the cover of the pizza box, you will find an array of little antenna gizmos where you normally would expect to find the pepperoni slices on a pizza. The pizza box mounts flat against the side of your building in a WLL (Wireless Local Loop) application, for instance. It also can mount on your rooftop in a satellite application. Hence, it is aesthetically pleasing. See also Phased Array and WLL.

PJ-327

A double RCA dipole plug for connecting a headset into a PBX console. When you buy a headset you need to specify ” 4-pin modular jack (for connecting to a telephone) or two prong plug (for connecting to a PBX console).

PKE

See Public Key Encryption.

PKI

See Public Key Infrastructure.

PKM

Programmable Key Module is an expansion module for a phone. Each expansion module adds a bunch speed dial buttons (in telecom a key is a switch or a button). Such modules typically come with 24, 48 or 654 speed dial buttons. The idea is to have zillions of speed dial buttons for your 64 closest business acquaintances . Such devices are often used in the brokerage business.

PL

Private Line.

PL/1

Programming Language One (IBM).

Place Call

There will be two types of calls: person calls and place calls. I make a place call when I call a phone number which ends in one designated, fixed RJ-11 jack attached to the wall or floor. I make a person call when I call a phone number which doesn't necessarily end on a fixed place. A typical person call might be a cellular or wireless phone call. It might also be a service like MCI's Personal 800 Service. The major characteristic of a person call is that I am calling a person and I don't know where that person is. As a result, the person I called might answer my call anywhere ” from his car, from vacation home, from his wireless phone, etc.

Plain B Wire Connector

Also called a B Connector or beans. A twisted-pair splicing connector that looks like a one-inch drinking straw. They have metal teeth inside them to pierce the vinyl insulation of the wire to make a good connection. Sometimes water-retardant jelly is sometimes place inside.

Plaintext

A message which is not encrypted. A message which is encrypted is called a ciphertext . See Clipper Chip.

Plan

A route to an end or objective usually achieved accidentally and often written in hindsight. Derived from the expression: "Most people spend more time planning their annual vacation than they do planning their careers."

Plan B

What happens if things don't work out as intended? Go to Plan B. No one knows where this expression came from.

Plan File

A file that lists anything you want others on the Internet to know about you. You place it in your home directory on your public-access site. Then, anybody who fingers (sees) you, will get to see this file.

Planar Array Antenna

A planar array antenna is designed for use at microwave frequencies. It resembles a double-sided printed circuit board. One side of the substrate carries an etched pattern of microstrip whilst the other is left completely metallic to act as a ground plane.

Planar Board

IBM's new name for a motherboard in their new series of System/2 Personal Computers. A motherboard is the main board in a PC on which the main CPU, the main memory, the clock and sundry other things like serial and parallel ports are mounted. Other boards, i.e. graphics boards, are plugged into the motherboard. Thus the expression "motherboard." No one knows why IBM dropped the word. Maybe it was too risque? Maybe they included more on their motherboards in the System/2 series that they would no longer function as motherboards? Maybe a feminist group of mothers objected?

Plane Management

An ATM term. As described in the ATM Protocol Reference Model, Plane Management is an element of the Management Plane. Plane Management acts on the management of the ATM switch, as a whole, without consideration of each of the various specific layers of the model. See ATM Protocol Reference Model for a graphic representation of the three-dimensional model.

Planned Communities

Imagine a large, empty piece of land. Imagine a developer coming along and building roads , sewage, electricity, telecommunications and several hundred houses . Bingo, we have a planned community. Planned communities are important because of the communities' telecommunications needs which may be provided by a central group with exclusive rights to provide phone, cable and data services to the community. That exclusive right has value. That's why several companies are going after the right to provide telecom service to planned communities. See also MDUs.

Plant

A general term for all equipment used by a telephone company to provide telecommunications services. In the telecom business, plant comes in two variations ” inside and outside plant. Inside is in a building. Outside is outside the building ” on poles, in the ground. Several people have asked me if the phone industry invented the term. The answer is no. The term has been around since the middle of the nineteenth century. It was used to describe all the implements of production. The third edition of the Oxford English Dictionary defines plant as "The fixtures, implements, machinery, and apparatus used in carrying on any industrial process; the premises and fixtures of a business or (chiefly U.S.) of an institution; a place where an industrial process is carried on; also, a single machine or large piece of apparatus..." See Inside Plant, Outside Plant and Plant Hump.

Plant Hump

A very friendly term for a craftsperson in a phone company ” installer, splicer , underground cable guy ” who works hard with outside phone equipment, often under adverse conditions and whose labors tend to be undervalued, particularly by the white collar , pencil pushers back at headquarters.In British slang, "hump" means to exert oneself. There is a badge of honor to being a "plant hump." These are the people who bring phone service to your door. The word plant hump is occasionally written as one word, i.e. Planthump. Other people who work for telephone companies are often called pencil pushers.

Plant Test Numbers

Virtually every 800 IN-WATS number has a plant test number. This is its equivalent seven digit local number. That number looks like a normal local seven digit number, with a standard three-digit central office exchange code and a four-digit extension. The purpose of plant test numbers is to allow the telephone company to test the local part of the incoming 800 number by simply dialing that number. For example, Miller Freeman, which published this dictionary has an 800 number ” 800-LIBRARY (or 800- 542-7279). The plant test number of the first line of that 800-LIBRARY group is 212-206- 6870. The second line is 212-206-6871 and so on. It is valuable to know the plant test numbers of your incoming WATS lines so you can test the local loop part of those lines. The local loop part is the part which typically gives the most problem. It is, unfortunately , the only part of your 800 lines you can test yourself ” unless you ask someone (or several people) to call you regularly on your 800 lines, just to test them. You can get plant test numbers out of your local and/or your long distance carrier. When they tell you those numbers are "not available," beg a little. They are available and you are entitled to them. Calling plant test numbers costs exactly what a normal long distance IN-WATS call on that line costs. So keep your test calls short. You should call your plant test numbers once a day.

Planthump

A colloquial word for a telephone company craftsperson. It derives from the term "plant," a telephone company word used to describe their "factory" ” i.e. everything from their inside plant, their central office switch, to their outside plant, which includes wire strung on telephone poles. In British slang, "hump" means to exert oneself. Planthump is a term of endearment in the telephone industry. Definition courtesy, Steve Marcus, New York Telephone, now called Bell Atlantic. The term is often spelled as two words, i.e. plant hump.

PLAR

Private Line, Automatic Ringdown. In telecommunications, leased voice circuit that connects two single instruments together. When either handset is lifted, the other instrument automatically rings.

Plasma

A low-density gas in which the individual atoms are ionized (and therefore charged), even though the total number of positive and negative charges is equal, maintaining an overall electrical neutrality. See Plasma Display.

Plasma Display Panels

PDPs. Type of flat visual display device in which selected electrodes, part of a grid of crisscross electrodes in a gas-filled panel, are energized, causing the gas to be ionized and light to be emitted . Some computers use plasma displays. They're fabulous, and expensive. See Plasma Display Panels.

PDPs. Plasma gases composed of helium, neon and xenon are sandwiched into cells between two vertical glass plates. Bursts of electricity are applied between transparent electrodes attached to one pane of glass. These bursts causes the plasma gases to emit ultra - violet rays. This activates red, blue and green phosphor dots, which emit visible light and form pictures on the screen. The more common cathode ray tube technology (e.g. computer monitors) uses an electron gun to direct a beam that lights up phosphors on a screen. Directing that beam requires CRT sets to be deep, heavy and unwieldy.

Plasmatron

The name Sony chose for a flat screen display it demoed at Comdex in the fall of 1995. The screen measured 20 inches diagonally. It was as bright as normal CRT screen, but was less than four inches wide. It is the beginning of flat screen entertainment screens for the home. It was spectacular.

Plaster Ring

A metal or plastic plate that attaches to wallboard for the purpose of mounting a telecommunications outlet box.

Plastic Optic Fiber

See POF.

Plasticizer

A chemical agent added in compounding plastics to make them softer and more flexible.

Plat

1. An imaging term. When a CAD/CAM plotter prints a large drawing, it's called a plat.

2. A map or plan of a small piece of ground showing boundaries, area, remainder, ownership, access, and other pertinent information.

Plate

The anode in a vacuum tube, which collects the electrons emitted by the filament.

Plate Battery

The source of E.M.F. connected in the plate circuit to give the plate element its positive charge.

Plate Voltage

The potential applied to the plate of the vacuum tube by the plate voltage supply.

Platen

A cylinder in a printer or typewriter around which the paper goes and which the printing mechanism strikes to produce an impression .

Platform

Platform is a loosely-defined word for a software operating system and/or open hardware, which an outsider could write software for. Windows98 is a platform. So is Windows 2000. If every phone system were a platform, then every owner of that phone system could write software for his phone system or buy outside-produced software and have his phone system work more to his liking. That's the objective of creating a "plat- form." See also OAI and Platform Independence.

Platform Agnostic

Several other developers in the wireless industry have created their own proprietary de-velopment platforms, or application pipelines, leaving carriers with more non-standard platforms to evaluate than content to deploy. This has created an environment with very few developers willing to commit their resources to any specific platform. Those devel -opers that do create an application must find a way to monetize their creation, a process that usually involves a relationship with carriers. Such relationships are extremely diffi-cult to develop, as carriers often will not deal with small companies that have little or no established reputation. This difficult environment has contributed to slow consumer adop-tion of wireless data services, and the slow deployment of the 3G networks that require killer applications to justify the expense of upgrading a network. We believe that closed and proprietary approaches are flawed, and that profitable compa-nies will create applications that run on existing platforms - instead of creating platforms themselves . This agnostic stance is Chasma's major advantage, because Chasma's ap-plications can generate revenue immediately upon distribution and are not dependant on carriers deploying any technology that is proprietary to Chasma.

Platform Wars

Your PDA works on Palm OS. Mine works on Windows CE. Which one will succeed in the long run is the one with the most number of useful software applications running on them. The only war to get outside software developers to write for my platform is to convince them that I've won the platform war ” the war between Palm OS and Windows CE. There are similar "wars" in PCs and in cell phones.

Platform for Privacy

See P3P.

Platform Independence

A term from IBM and Metaphor Computer Systems. The idea, they say, is to produce a layer of software that would rest atop any operating system on any piece of hardware. The applications developers would write their software just once, rather than start from scratch each time they wanted get their software working on a different computer. If the whole idea sounds rather daunting, you're right.

Platter

The round magnetic disk surfaces used for read/write operations in a hard disk system.

Play Off

In voice processing, in response to questions such as "Press one for Harry," the user touchtones buttons on his phone. Those buttons generate DTMF (Dual Tone Multi- Frequency) tones. The system has to figure out what the person "said" with his touch- tones. The tricky part of DTMF detection is distinguishing between tones generated from an actual "key press" and "tones" caused by speech. Mistaking a person's speech (as in leaving a message) for DTMF is called "talk-off." Mistaking a person's recorded speech (as in playing back a message) for DTMF is called "play-off."

You can imagine the havoc poor DTMF detection can cause a voice processing system. For example, if touchtoning three means "delete this message" and while playing the message, the system incorrectly detects a portion of the message playback as the touchtones for a key press three, I'll delete the message when I had intended to listen to it. On the other hand, if I'm listening to a message and want to delete it prior to finishing the message, I want the system to detect my key press three as the real thing and go ahead and delete the message.

Playback

Retrieval, decoding and transmission of encoded data. It is also a multimedia term. Playback is the process of viewing multimedia materials created by an author. Playback can include a range of activities, from viewing a single video clip to participating in a series of interactive multimedia training modules. Some playback applications (for example many training and presentation applications) are sold separately from their authoring applications. However, many developers are selling authoring and playback capabilities in a single product.

Playback Head

The part which converts the magnetic information on the tape or disk into an electrical signal. Moving the magnetic fields on the medium (tape or disk) past the playback head generates a tiny voltage, which is picked up in a conductor (a coil) in the payback head and sent onto the electronic equipment where it is amplified or transmitted.

Player

An SCSA definition. A resource object that plays TVM data. The audio data can come from a voice or audio encoded file, or from text that has passed through a text-to- speech service. The output of a player can be analog audio, TDD, ADSI, etc.

Playtester

A person who tests computer games , either for free or for a living. I first saw the term when Microsoft was sending out emails looking for " playtesters " for its Xbox electronic game ” the one meant to compete with the Sony Playstation.

PLC

Planar Lightwave Circuit.

PLCP

Physical Layer Convergence Protocol. The part of the physical layer that adapts the transmission facility to handle DQDB functions as defined in IEEE 802.6-1990. It is used for DS-3 transmission of ATM. ATM cells are encapsulated in a l25microsecond frame defined by the PLCP which is defined inside the DS3 M-frame.

PLD

Programmable logic device. PLDs used to be slow, big and expensive. Now they can be customized using a PC and their performance is close to that of the ASIC. See ASIC.

PLDS

Private line data circuit. I don't know why it's an S, not a C.

PLeasure

All pleasure is sin, according to John Calvin.

Plenum

In some modern buildings , the ducts carrying the heat return are not metal ducts but actually are part of the ceiling. This is called a plenum ceiling. Most cities now have rules and regulations which say that if you run cabling through these plenum ceilings, you must not use cabling sheathed in PVC (polyvinyl chloride), the standard jacketing of most electrical cable. The reason is that PVC burns and emits toxic smoke ferociously. Plenum cable is low smoking so that if it catches fire it won't circulate toxic smoke through the vent system and suffocate everyone. Plenum cabling is often made of teflon. It's much more expensive than normal cabling. See also FEP and NFPNA 90A.

Plenum Area

The space between the drop ceiling and the floor above. Continuous throughout the length and width of each commercial building floor.

Plenum Cable

Cable specifically designed for use in a plenum (the space above a suspended ceiling used to circulate air back to the heating or cooling system in a building). Plenum cable has insulated conductors often jacketed with polyvinylidene diflouride (PVDF) material to give them low flame spread and low smoke-producing properties. Burn a normal PVC cable and it will give off a vile, toxic smoke that can kill. Many buildings and many cities stipulate that only plenum cable can be installed in the plenum in the ceilings. Plenum cable has fully color coded insulated copper conductors and is available in various pair sizes.

Plesiochronous

Plesiochronous, based on Greek and Latin roots, roughly translates as "more together in time." Plesiochronous networks involve multiple digital synchronous circuits running at different clock rates. For instance, a Verizon T-1 circuit may meet a MCI T-1 circuit, with each taking making use of a different clocking source. Also for example, multiple MCI T-1 circuits may require multiplexing into a T-3 circuit; with the T-1's and the T-3 running at different clock speeds. In either case, the differences in clock speeds must be resolved through the use of a master clocking source such as a Stratum I clock, which relies on a highly reliable cesium clocking source. T-carrier and E-carrier networks are plesiochronous. Compare to Synchronous, Asynchronous and Isochronous. See also PDH.

Plesiochronous Networks

Network elements that derive timing from more than one primary reference source. Network elements accommodate minor frequency differences between nodes.

PLL

Phase Locked Loop: Phase Locked Loop is a mechanism whereby timing information is transferred within a data stream and the receiver derives the signal element timing by locking its local clock source to the received timing information.

PLLC

Professional Limited Liability Corporation, as in a law firm.

PLMN

Public Land Mobile Network. A mobile telephone communications network established by a provider to facilitate mobile telecommunications services. This includes equipment, operations, and staff. A single provider may have more than one PLMN.

PLMR

Private Land Mobile Radio system.

Plotter

A type of computer peripheral printer that displays data in two-dimensional graphics form.

PLS

Premises Lightwave System.

PLSC

Private Line Service Center.

PLTS

Private Line Transport Service. Non-switched communications channel from one customer location to another. May be leased from a Local Exchange Carrier or Interexchange Carrier.

PLU

See Percent of Local Usage.

Plug

A male element of a plug/jack connector system. In the Premises Wiring System it provides the means for the user to connect his communications devices to the Communications Outlet as well as the means to disconnect his service at the Network Interface Jack when trouble analysis is required.

Plug 'N Play

1. Manufacturers' concept of how easy it is to install their equipment. "Why it's just plug 'n play," says the manufacturer. In reality, nothing, absolutely nothing, is plug 'n play. It's a fantasy concept. See Plug and Play.

2. Also defined as a new hire who doesn't need any training. "The new guy, Harry, is great. He's 100% plug-and-play."

Plug And Play

This explanation comes from an Intel Technology Primer: Since addin cards first appeared over a decade ago, they've given users a lot of different ways to improve their PCs and given them a lot of installation headaches . In this brief, we'll tell you how Intel, together with industry leaders , has spent years developing Plug and Play technology to make add-in cards both easier to use and install. Never before has the PC had as many capabilities as it does today. That's due in part to the large number of add-in cards available, like those for multimedia and faxmodems. Yet, as more cards are added to a PC, their installation can become quite complex. Installing a card can be a time-consuming and technical process, and there's no guarantee it will even work the first time. Sometimes the user must configure the card manually, which means selecting a variety of system resources for each card. These include Interrupt Requests (IRQ), I/O and memory addresses, and Direct Memory Access (DMA) channels. Every PC has a limited number of these resources available. Each card is designed to use a small group of them. Assigning these resources means opening the computer and physically setting the jumpers and DIP switches. And since no standard has been set to determine which cards can use which resources, numerous conflicts can arise between cards. Often, it's a process of trial and error to determine which resources aren't already being used by other cards. Since the ISA bus was introduced, several new bus architectures have followed to solve the resource allocation problem. For example, the MCA and the EISA bus standards both defined a mechanism where add-in cards were configured somewhat automatically. These bus architectures allocated the resources, but the process wasn't always flexible and still required some manual intervention. And they still left the current ISA cards without a solution. Plug and Play technology, co-developed by Intel and other industry partners , consists of hardware and software components that card, PC, and operating system manufacturers incorporate into their products. With this technology, the user is responsible for simply inserting the card. Plug and Play makes the card capable of identifying itself and the resources it requires. The system's software automatically sets up a suitable configuration for the card. Newly developed PCI and Plug and Play ISA cards are all built to eliminate user intervention during the installation process. See Plug and Play Bios Extensions.

Plug And Play BIOS Extensions

Software code added to a PC's bios which purports to automatically recognize which peripherals are in the PC and automatically configure the PC for those peripherals ” without the need for fiddling with dip switches or setting interrupts, etc. Plug and Play comes from Intel. And more and more PC cards are coming Plug and Play compatible.

Plug Compatible

Devices made by different manufacturers that are totally interchangeable. The word derives from the fact that the devices are so completely interchangeable that you can simply unplug one device and plug in another device made by different manufacturer and it will work the same, or better.

Plug-in

A program of data that enhances, or adds to, the operation of a (usually larger) parent program. A paint package, for example, might contain plug-in tools that create special effects, like speckling. A Web browser might have a plug-in that allows you to hear sound or view movies you download over the Internet. There are hundreds of plug-ins. See www.netscape.com/plugins/index.html

Plugboard

A telephone switchboard on which connections are made by a jack and an attached cord representing a trunk (the male jack and the cord) and a female plug (the telephone extension). Early plugboards needed an operator to place outside calls and connect incoming calls. All calls were completed by the operator. Plugboards were common in the days of "PBXs." Then came PABXs (Private Automated Branch Exchanges) and you could dial out without the help of an operator. Then electronic PABXs came in and you could dial directly in to many internal extensions, using a feature called DID (Direct Inward Dial). Now PABXs are called PBXs because they're all automatic. Plugboards are rapidly disappearing . They do have two great uses, however. First, operators who grew up with them, still like them. Operators who now live in nursing homes like them. Second, because the jack and plug make a pure metallic connection, they're great for data transmission and occasional data switching.

Plugs

Circuit cards which control various aspects of transmission and carrier circuit functionality and usage.

Plumber's Crack

Imagine a fat plumber dressed in jeans. When he leans forward, exposing the top part of his bottom. That is called plumber's crack. Longer tea shirts and higher jeans have been designed to cover plumber's crack, since the industry has found that its customers ” suburban housewives ” are often offended by the sight.

Plumbing software

If your business is like Technology Investor Magazine, it has different software programs for each business task ” accounting, sales automation, order entry, inventory, etc. If you could get those pieces of software to talk to each other, and to talk sense to each other, you could save time, lower labor costs, improve your products and provide better customer service. Better yet, if you could get your internal software programs talking to software at your suppliers and customers, you could save even more money, labor and time. That's what integration software does. Every business of any size can use it to improve how their business works. There are three types of integration software: enterprise application, business-to-business, and business-to-community. What's the difference? All integration software lets two or more software applications ” e.g. accounting and inventory ” exchange (transport) and understand (transformation) each other's data. That's why it's often called plumbing software.

PLV

An imaging term. Production Level Video. DVI Technology's highest quality motion video compression algorithm. It's about 120-1 compression. Compression is done "off- line". i.e. non-real time, and playback ( decompression ) is real time. Independent of the technology in use, off-line compression will produce a better image quality than real time since more time and processing power is used per frame.

PLY

One layer in a composite.

PM

1. Physical Medium: Physical Medium refers to the actual physical interfaces. Several interfaces are defined including STS-1, STS-3c, STS-12c, STM-1, STM-4, DS1, E1, DS2, E3, DS3, E4, FDDI-based, Fiber Channel-based, and STP These range in speeds from 1.544Mbps through 622.08 Mbps.

2. Performance Monitoring. Gives a measure of the quality of service and identifies degrading or marginally operating systems (before an alarm would be generated). Digital signal parameters, including errored seconds and out of frame, measure the integrity of a communication channel as defined in AT&T Compatibility Bulletin 149 (CB 149).

3. Peripheral Module.

4. An ATM term for the Physical Medium sublayer. See Physical Medium.

PMA

Positive Mental Attitude. Todd Kingsley has it. I know because he told me so. He said he was positively mental.

PMC

Public Mobile Carrier.

PMD

1. Physical Medium Dependent. This PHY (PHYsical Layer) sublayer defines the parameters at the lowest level, such as speed of the bits on the media. See also PHY.

2. Polarization Mode Dispersion. A fiber optic term describing distortion created by irregularities in the shape of the fiber optic cable and its core; the problem is exacerbated by splicing, expansion and contraction of the cable due to variations in ambient temperature, and spooling of the cable. At high transmission speeds (e.g., SONET OC-192) digital light pulses can suffer from PMD. As the pulses travel down the fiber, the cable's physical irregularities cause delays on the at the outer edges of the core ; the center portion of the pulse which travels through the "sweet spot" is unimpaired and, therefore, travels at a higher rate of speed from end-to-end. The result is that portions of an individual light pulse can arrive at slightly different time, with the delay being measured in picoseconds. The effect is one of distortion as the center portion of subsequent light pulses can overrun the outer portions of the preceding pulses. The impact is a higher bit error rate (BER). PMD is especially a problem at high transmission speeds, and particularly over older fiber optic cables deployed prior to the anticipation of high-bit rate SONET. Confused ?...Consider the following explanation: If you drop a perfectly round rock into a pond of water, the waves run at the same speed toward the edges of the pond. If the pond is not perfectly round, some waves will reach the bank before other waves. If you now think of shooting the rock into a water pipe, you can see that some of the resulting compression waves will reach the other end before others. The combination of resistance at the edges of the pipe and irregularities in the shape of the pipe act to compound the problem, which varies unpredictably from pipe to pipe. See Chromatic Dispersion.

PMI

Project Management Institute.

PML

Physical Markup Language. An Auto-ID Center-designed method of describing products in a way computers can understand. PML is based on the widely accepted eXtensible Markup Language used to share data over the Internet in a format all computers can use.

PML Server

A server that responds to requests for Physical Markup Language (PML) files related to individual Electronic Product Codes. The PML files and servers will be maintained by the manufacturer of the item.

PMMU

Paged Memory Management Unit. Macintosh computers equipped with a PMMU may use virtual memory with the System 7 operating system.

PMN

Indicates loss of ac power at the far-end terminal.

PMP

1. Point-to-MultiPoint. An ATM term describing the connecting circuitry between a single end point (root node) and multiple end points (leaf nodes). The root node can transmit data over a PMP connection to multiple leaf nodes, usually through a switch or router. The leaf nodes can transmit back to the root node, but do not have the ability to transmit data directly to other leaf nodes.

2. Project Management Professional as certified/designated by the Project Management Institute (PMI).

PMR

1. Poor Man's Routing. A technique used in any packet-switched networks to allow a source node to predefine the routing to the destination, bypassing the normal routing algorithm implemented at the network layer.

2. Private Mobile Radio. The European term for what in the US is called Specialized Mobile Radio (SMR) or Trunk Mobile Radio (SMR). See SMR and TETRA.

PMS

1. Picturephone Meeting Service. An AT&T service once provided under experimental tariff. It combined TV techniques with voice transmission. PMS is usually only available between telephone company-located picturephone centers. Most have now been closed down. The venture was losing too much money.

2. Property Management System, a software program and computer that controls all guest billing and guest services functions in a hotel. In short, the guts of a hotel's computer system. Some telephone systems have a PMS Interface, which allows various degrees of integration between the telephone system and the hotel's computer systems. For example, voice mail could be administered through the hotel's Property Management System.

3. The Pantone Matching System, a universal language for solid-color specification and reproduction. Colors defined by PMS receive a unique number and mixing formula. Consequently, when artists specify a PMS number they can be sure that the final printed product will match the chosen color. But, be careful, PMS colors look different when printed on different papers. The biggest perceived difference is when you print on glossy or matte paper.

PMS Interface

An interface that allows telephone system functions (like voice mail) to be administered through a hotel's Property Management System.

PN

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

PNG

Portable Network Graphics, pronounced "Ping." A graphics file format ending in .png, which was developed to overcome deficiencies of .gif and .jpeg file formats, which are commonly used on the Web. PNG, under development by the W3C, allows 16-, 24-, and 32-bit images, providing for better color depth. The downside is that higher-quality images require more storage and involve longer download times. PNG overcomes this problem through the use of better image compression technology.

PNI

An ATM term. Permit Next Increase: An ABR service parameter, PNI is a flag controlling the increase of ACR upon reception of the next backward RM-cell. PNI=0 inhibits increase. The range is 0 or 1.

PNNI

Private Network-to-Network Interface: PNNI is a routing protocol for ATM that allows for the exchange of routing information between ATM switches. PNNI allows those switches in the network to determine the best route to establish the type of connection needed. PNNI allows for switches from different vendors, or on different networks, to exchange addressing and routing information so those who maintain the network can set up connections with minimum fuss. In short, PNNI is a routing information protocol that enables extremely scalable, full function, dynamic multi-vendor ATM switches to be integrated in the same network. PNNI has two functions: to reliably distribute network topology information so that fast routing paths can be determined to any destination and second, to provide a signaling protocol to help set up point-to-point and point-to-multipoint connnections. The idea is enable simple network configurations while helping network personnnel efficiently manager the network's resources.

PNNI Protocol Entity

An ATM term. The body of software in a switching system that executes the PNNI protocol and provides the routing service.

PNNI Routing Control Channel

An ATM term. VCCs used for the exchange of PNNI routing protocol messages.

PNNI Routing Domain

An ATM term. A group of topologically contiguous systems which are running one instance of PNNI routing.

PNNI Routing Hierarchy

An ATM term. The hierarchy of peer groups used for PNNI routing.

PNNI Topology State Element

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

PNNI Topology State Packet

An ATM term. A type of PNNI Routing packet that is used for flooding PTSEs among logical nodes within a peer group.

PNM

Public Network Management.

PNO

Public Network Operator. Usually a PTT of some sort . See PTT.

PnP

Plug and Play. The technology that lets Windows 95 and soon other operating systems automatically detect and configure most of the adapters and peripherals connected to or sitting inside a PC. A fully Plug and Play-enabled PC requires three PnP pieces: a PnP BIOS, PnP adapters and peripherals, and a PnP operating system. Adding a PnP-compliant CD-ROM drive, hard disk, monitor, printer, scanner, or other device to a PnP PC means little more than making the physical connection. The operating system, together with PnP logic present in the BIOS and in the device itself, handles the IRQ settings, I/O addresses, and other technical aspects of the installation to make sure that the thing will work. The idea of PnP is to make installation of complex gadgets ” such as sound cards and modems ” easy, taking care of the major bane of everyone's life: That your new device now conflicts with an old device, effectively killing both devices and maybe crashing your PC at the same time. PnP is a great idea. Its success has been slow in coming, because so many devices are not PnP compatible.

PNS

Personal Number Service is a new concept in telecommunications that assigns a telephone number to a person, not a location, effectively allowing a subscriber to use one number for all calls and helping them manage their incoming communications. The service does not require the user to change any existing phone numbers. The subscriber simply provides the various numbers ” office, cellular, pager, fax and home ” and instructions on where and when the calls should be routed, and the PNS directs the calls in the order requested by the subscriber.

PO

1. Point of Origin. It is used in relationship with a Message Transfer Agent (MTA).

2. Post Office Location: City, State, ZIP.

POC

Points of Contact. The person or persons identified in a record. Sometimes this information is referred to as "Person Objects." See also InterNIC.

Pocket Bongo

Picture a group of people. Suddenly, something on someone beeps. But the someone doesn't know (or pretends not to know) which of the many wireless devices he's carrying that is bleating. Is it the cell phone? Or the pager? Or the PCS phone? The person starts patting himself all over, with mock embarrassment. But his look screams, "I'm wired and I'm proud." His behavior is called "pocket bongo." I read about pocket bongo first in an article by Joan Hamilton in the February 15, 1999 issue of Business Week. The article was headed, "We've got a bad case of digital gizmosis."

Pocket Call

A call made when a cell phone's buttons are depressed as it jostles around in a pocket or purse. Because many handsets speed-dial 911 at the touch of a button, the calls are an ongoing problem for emergency lines.

POCSAG

Post Office Code Standardization Advisory Group. A one-way paging protocol that supports numeric and text paging at data rates of 512, 1,200,and 2,400 bits per second. Most traffic occurs at 1,200 bits per second. It is one of the communications protocols used between paging towers and mobile pagers /receivers/beepers themselves. Other protocols are GOLAY, ERMES, FLEX and REFLEX. The same paging tower equipment can transmit messages one moment in POCSAG and the next moment in ERMES, or any of the other protocols.

PODP

Public Office Dialing Plan.

Podiumware

You're presenting a great speech detailing some great new concept in hardware or software. You don't have many precise details, except your vague words. This is called podiumware. When your thinking has become more concrete, and you make slides on your new hardware or software, you have moved to slideware. Eventually when you announce your new hardware or software, you have moved to hypeware or vaporware. I was first introduced to the word "podiumware" by Bob Lewis, a columnist for InfoWorld Magazine. See also Hookemware, Hyperware, Meatware, Podiumware, Shovelware, and Vaporware.

POF

Plastic Optic Fiber. A fiber optic transmission medium made from plastic, rather than glass, POF is evolving as a replacement for twisted-pair copper wire. Glass clearly (double entendre intended) performs better than plastic, as it offers less attenuation and, therefore, better transmission quality at higher speeds and over longer distances. Plastic, however, is less expensive, less susceptible to breakage , and is highly tolerant of temperature extremes. The ATM Forum has approved specifications for 155-Mbps ATM transmission over POF for distances up to 50 feet.

POFS

Private Operation Fixed Systems. Microwave incumbents in the 2.0 Ghz band . Must be relocated with comparable alternative facilities funded .

POGO

Post Office Goes Obsolete. When MCI Mail was originally being planned, its code name was POGO. The idea was obvious. In September of 1994, I asked MCI what "POGO" meant and they answered: "Pogo" is an internal message format used by MCI for coding purposes.

POH

Path OverHead. SONET overhead assigned to and transported with the payload until the payload is demultiplexed. It is used for functions that are necessary to transport the payload; i.e., end-to-end network management. These functions include parity check and trace capability. It is not implemented in SONET Lite.

POI

1. Point Of Interface. The physical telecommunications interface between the LATA access and the interLATA functions. A POI is a demarcation point between LEC and a Wireless Services Provider (WSP). This point establishes the technical interface, the test point(s) and the point(s) for operational division of responsibility. See also Point of Presence.

2. Parallel Optic Interfaces. POI is a relatively cheap technique for optical transmission at high speeds over VSR (Very-Short-Reach) links of 300 meters or less. The technique makes use of multiple MMF (MultiMode Fiber) links, over which an optical signal at speeds up to 10 Gbps (OC-192) is spread across multiple fibers at the same wavelength through inverse multiplexing. The technique is considered to be low cost, as the MMF is much less expensive than the SMF (Single Mode Fiber) that normally is required to support such speeds, and as the quantum-well VCSELs (Vertical-Cavity-Surface-Emitting Lasers) also are low cost. The applications are in the interconnectivity of collocated devices such as switches, optical cross-connects, routers. See also MMF, SMF, VCSEL, and VSR.

Point Code

A SS7 term for a unique code which identifies a network node in order that the SS7 network can route calls properly. When placing a call, you dial a Global Title in the form of dialed digits (i.e., a telephone number). Those digits are translated from the Global Title to a Point Code by the STP (Signal Transfer Point) through a process known as Global Title Translation (GTT). See also Global Title, Global Title Translation, SS7, and STP.

Point In Call

PIC. A representation of a sequence of activities that the ASC (AIN Switch Capabilities) performs in setting up and maintaining a basic two-party call. PICs occur in Originating and Terminating BCSMs (Basic Call State Model).

Point of Demarcation

Physical point at which the phone company's responsibility for the wiring of the phone line ends.

Point Of Interface

POI. The physical telecommunications interface between the LATA access and the interLATA functions. A POI is a demarcation point between LEC and a Wireless Services Provider (WSP). This point establishes the technical interface, the test point(s) and the point(s) for operational division of responsibility.

Point Of Presence

POP. A physical place where a carrier has a presence for network access, a POP generally is in the form of a switch or router. For example, an large IXC will have a great many POPs, at which they interface with the LEC networks to accept originating traffic and deliver terminating long distance traffic. The basis on which the interface is accomplished can include switched and dedicated (leased line) connections. Similarly, providers of X.25, Frame Relay and ATM services have specialized POPs, which may be collocated with the circuit-switched POP for voice traffic. A POP also is a meet point for ISPs (Internet Service Providers), where they exchange traffic and routes. See also GIGAPOP and POP.

Point Of Purchase Politics

Politically correct shopping or cause-related marketing, such as that advocated by Benetton or Ben and Jerry's.

Point Of Sale Terminal

A special type of computer terminal which is used to collect and store retail sales data. This terminal may be connected to a bar code reader and it may query a central computer for the current price of that item. It may also contain a device for getting authorizations on credit cards.

Point Of Termination

POT. The point of demarcation within a customer-designated premises at which the telephone company's responsibility for the provision of access service ends.

Point Size

The height of a printed character specified in archaic units called "points." A point equals approximately 1/72 inch. Also known as font size. See also Font.

Point To Multipoint

A circuit by which a single signal goes from one origination point to many destination points. The classic example is a TV signal (say a Home Box Office program) being broadcast from one satellite to many CATV subscribers all around the country. Not to be confused with a multi-drop circuit. See Point to Point Multipoint Connection.

Point To Multipoint Connection

A Point-to-Multipoint Connection is a collection of associated ATM VC (Virtual Channel) or VP (Virtual Path) links, with associated endpoint nodes, with the following properties:

1. One ATM link, called the Root Link, serves as the root in a simple tree topology. When the Root Node sends information, all of the remaining nodes on the connection, called Leaf Nodes, receive copies of the information.

2. Each of the Leaf Nodes on the connection can send information directly to the Root Node. The Root Node cannot distinguish which Leaf is sending information without additional (higher layer) information. (Note: UNI 4.0 does not support traffic sent from a Leaf to the Root.)

3. The Leaf Nodes cannot communicate directly to each other with this connection type. See ATM.

Point-to-Multipoint Delivery

Delivery of data from a single source to several destinations.

Point-To-Point

A private circuit, conversation or teleconference in which there is one person at each end, usually connected by some dedicated transmission line. In short, a connection with only two endpoints. See also Point-To-Multipoint.

Point-To-Point Connection

An uninterrupted connection between one piece of equipment and another.

Point-To-Point Delivery

Delivery of data from a single source to a single destination.

Point-To-Point Protocol

See PPP.

Point-To-Point Signaling

A signaling method where signals must be completely received by an intermediate station before that station can set up a call connection. See End to End Signaling.

Point-To-Point Topology

A network topology where one node connects directly to another node.

Point-To-Point Tunneling Protocol

PPTP. Part of the VPN suite, a protocol by which tunnels are established and terminated over the Internet. An alternative to IPsec, L2TP, SOCKSv5 tunneling protocols. See PPTP for more detail.

Pointcasting

First, there was broadcasting. One signal went to many people. Radio and TV are the classic concepts of broadcasting. One signal ” the same signal ” to many people. Then came the idea of narrowcasting. One signal to a select number of people ” maybe only those people who subscribed to the service and had the equipment to receive it. Then there came pointcasting. This is a fancy name for sending someone a collection of customized information ” snippets of stuff that they chose from a palette of information offerings.

Pointer Processing

Pointer processing accommodates frequency differences by adjusting the starting position of the payload within the frame. A pointer keeps track of the starting position of the payload.

Pointing Stick

Alternative to an external mouse and similar to a miniature joystick. You can use the tip of your finger to move the rough textured eraser sized pointer in the direction you want the cursor or arrow to go.

Points of Contact

The person or persons identified in a record. Sometimes this information is referred to as "Person Objects." See also InterNIC.

Points Of Failure

A simple term to indicate that in a complex network there are many places things can go wrong. Those places need to be identified so that you can anticipate and plan for things to go wrong. Points of failure (with or without the hyphens) should not be confused with a "Single Point of Failure". Single Points of Failure should be eliminated by establishing proper redundancy. "Points of failure" refer to the points within a single path of communication or operation. That single path is the "Single Point of Failure". So to maximize efficiency while minimizing downtime the architecture would minimize the "Points of Failure" by eliminating process steps within a path or operation. And at the same time eliminate a "Single Point of Failure" by providing a redundant path or operation.

Poison Pill

A poison pill is a strategy used by corporations to discourage the hostile takeover by another company by making its stock less attractive to the acquirer. There are basically two types of poison pills: First, "flip-in", which allows existing shareholders (except the potential acquirer) to buy more shares at a discount. Second, the "flip-over" allows stockholders to buy the acquirer's shares at a discounted price after the merger. By buying more shares cheaply (flip-in), investors get instant profits and more importantly, they dilute the shares held by the potential acquirer, thus making the takeover attempt more difficult and expensive. An example of a flip-over is when shareholders have the right to purchase stock of the acquirer on a 2-for-1 basis in any subsequent merger. A poison pill is often called a shareholder rights plan. Companies propose all sorts of reasons for swallowing poison pills. For example, Delphi Automotive told its shareholders, "in order for Delphi to deliver stockholder value, Delphi must have the opportunity to execute its strategic business plan without the distraction of unfair, imprudent or abusive takeover attempts, particularly in an industry that is currently undervalued. In addition, the market needs some time to understand that Delphi is not just an auto parts company but a technology company, and to value it accordingly ."

Poison Reverse

Announcement state in EIGRP when an advertisement within the EIGRP network becomes unreachable, at which time it is assigned a metric of "infinity" so routes destined for that network take alternate paths.

Poisson

See Poisson Distribution.

Poisson Distribution

A mathematical formula named after the French mathematician S. D. Poisson, which indicates the probability of certain events occurring. It is used in traffic engineering to design telephone networks. It is one method of figuring how many trunks you will need in the future based on measurements of past calls. Poisson distribution describes how calls react when they encounter blockage (see QUEUING THEORY for a detailed explanation of blockage). There are two main formulas used today in traffic engineering: Erlang B and Poisson. The Erlang B formula assumes all blocked calls are cleared. This means they disappear, never to reappear. The Poisson formula assumes no blocked calls disappear. The user simply redials and redials. If you use the Poisson method of prediction, you will buy more trunks than if you use Erlang B. Poisson typically overestimates the number of trunks you will need, while Erlang B typically underestimates the number of trunks you will need. There are other more complex but more accurate ways of figuring trunks ” Erlang C (blocked calls delayed or queued) and computer simulation. Poisson has been used extensively by AT&T to recommend to its customers the number of trunks they needed. Since AT&T was selling the circuits and preferred its customers to have excellent service, it made sense to use the Poisson formula. As competition in long distance has heated up, as circuits have become more costly and as companies have become more economically-minded (more aware of their rising phone bills), Poisson has become widely ignored.

After I wrote the above definition, Lee Goeller, a noted traffic engineering expert contributed the following definition of Poisson Distribution: A probability distribution developed by E.C. Molina of AT&T in the early 1900s for use in solving problems in telephone traffic (see TRAFFIC ENGINEERING), although it has many other uses and is widely applied in many fields. When made aware of Poisson's prior effort (circa 1820), Molina gave him full credit and even taught himself French so he could read Poisson in the original. The Poisson distribution assumes a call is in the system for one holding time, whether it is served or not (blocked calls held); the first form of the distribution estimates the probability that exactly X calls will be in the system, while the second estimates the probability that X or more calls will be present. If there are only X trunks to serve the calls, the second form gives the probability of blocking. Although limited tabulations of the Poisson distribution had been made earlier, Molina published an extensive set of tables in 1942. The Poisson distribution slightly overstates the number of trunks needed when compared to the Erlang B distribution (see Erlang B).

Poisson Process

A kind of random process based on simplified mathematical assumptions which makes the development of complex probability functions easier. In traffic theory, the arrival of telephone calls for service is considered a Poisson process. Calls arrive "individually and collectively at random," and the probability of a new call arriving in any time interval is independent of the number of calls already present. A Poisson process should not be confused with the Poisson Distribution, which gives the probability that a certain number of calls will be present if certain additional assumptions are made. See Poisson Distribution.

Poke

When you store a number in memory you "poke" it there. When you want to read it back, you take a "peek." Peek and poke are thus instructions that view and alter a byte of memory by referencing a specific memory address. Peek displays the contents; poke changes it.

Poke-Through Method

A distribution method that involves drilling a hole through the floor and poking cables through to terminal equipment from the ceiling space of the floor below. See also Ceiling Distribution Systems and Newton.

Poke-Through System

Penetrations through the fire-resistive floor structure to permit the installation of horizontal telecommunications cables.

Pokemon

A Jamaican proctologist.

Polar Keying

A transmission technique for digital signals in which the current flows in opposite directions for 1s and 0s or marks and spaces. It is used in telegraph signaling. It is also known as polar transmission.

Polar Plot

A 360-degree graph measuring direction by angle and levels using concentric circles.

Polar Relay

A relay containing a permanent magnet that centers the armature. The direction of movement of the armature is governed by the direction of current flow.

Polarity

Which side of an electrical circuit is the positive? Which is the negative? Polarity is the term describing which is which. Knowing polarity is not critical with rotary phones. They will work irrespective of which way the telephone circuit's polarity is. Touchtone phones, however, need correct polarity for their touchtone pads to work. How to tell? If you can receive an incoming call, can speak on the phone clearly, but can't "break" dial tone by touching a digit on your touchtone pad, then the polarity of your line is reversed. Simply reverse the red and green wires. Some electronic phones behind PBXs and key systems are also sensitive to polarity. If in doubt, simply reverse the wires. In video, reversed polarity results in a negative picture.

Polarization

Polarization is the direction of electric field in a radiated wave. This direction may be constant or may rotate as the wave propagates (resulting in linear, circular or elliptical polarizations). Polarization considerations apply whether a signal is transmitted (or received) in air, cable, fiber, waveguide or other transmission media. Polarization matters because it is one factor in determining how much energy an antenna receives from an incoming signal. If the polarization of the receiving antenna matches the polarization of the incident wave, no energy lost due to polarization mismatch (such an antenna and wave are referred to as "co-polarized"). However, where the polarization of the receiving antenna is orthogonal to the polarization of an incident wave, no energy will be received by the receiving antenna (such an antenna and wave are referred to as "crosspolarized"). The interesting thing is that cross-polarization can occur between an antenna with vertical linear polarization versus a wave with horizontal linear polarization, as well as between waves/antennas with left/right handed circular polarizations. Consequently, polarization is a major consideration in antenna system design. Thanks to Paul Chandler for help on this definition.

Polarization Beam Combiner

PBC. A PBC is capable of combining pump laser inputs with orthogonal polarization states. A PBC combines the signal strength of two low- powered 14XX nanometer pump lasers, producing a signal with double the power. PBCs can be used in both EDFAs and Raman amplifier modules, achieving higher output power from less costly, more readily available pump lasers. See Laser and Raman Amplifier .

Polarmount

A polarmount is a moveable dish antenna mount that allows a dish to be moved to different satellites . Azimuth and elevation are automatically adjusted as the dish moves.

Pole Attachment

Cost to cable TV, cellular provider and other telecom operators (including end users) to rent space to attach cables to telephone company and power company poles. There are charges and often significant restrictions on the attachment of your cable to their pole.

Pole Hug

See Spurring Out.

Policy Decision Point

See COPS and PDP.

Policy Enforcement Point

See PEP.

Policy Routing Protocol

An extension of Vector Distance Protocols used in router networks. Used primarily in Internet routers, Policy Routing Protocols determine the route of a packet in consideration of "permissions" and reciprocal business contracts between and among backbone carriers, ISPs and Internet Access Providers. In other words, the route is determined on the basis of non-technical policy, rather than the number of hops a packet must travel. Assuming that the intercarrier policy accepts the offered traffic, the packet is routed based on technical considerations according to Vector Distance Protocols. Examples of Policy Routing Protocols include BGP (Border Gateway Protocol) and IDRP (InterDomain Routing Protocol). See also Distance Vector Protocol, Link-State Protocol, and Router.

Policy-Based Networking

Also known as Policy-Based Routing (PBR) and Policy-Based Network Management (PBNM). A traffic management concept involving the establishment of priorities for network traffic based on parameters such as traffic type, application, and user ID. ATM does a great job of policy-based networking as a result of QoS (Quality of Service) levels. RSVP (Resource ReserVation Protocol) from the IETF is emerging as a solution to managing traffic priorities over the Internet. Policy-based networking can be implemented in capable switches, routers and servers. See also OOPS, RSVP and QoS.

Policy-Based Quality of Service

A network service that provides the ability to prioritize different types of traffic and manage bandwidth over a network.

Polishing

Preparing a fiber end by moving the end over an abrasive material.

Politeness

The most acceptable hypocrisy. Mostly seen before the sale.

Political File

Records required by Section 76.207 which relate to origination cable- casts by, or on behalf of, candidates for public office. This rule requires each cable television system to keep a record, in its PIF, of all requests for cablecast time, together with detailed supporting information.

Politically Correct

PC. The art of saying something totally bland when a good insult would be more satisfying , and more deserved.

Politician

John Maynard Keynes said that politicians are apt to be slaves to the ideas of long-deceased economists. John Kenneth Galbraith defined economists as people who didn't have the personality to become accountants .

Politics

1. A clash of self-interests masquerading as a clash of principles.

2. The technique by which most telephone systems are bought in large corporations.

3. Poli in Latin means 'many' and 'tics' meaning 'bloodsucking creatures ', which seems to accurately describe the process.

Poll

In data communications, an individual control message from a central controller to an individual station on a multipoint network inviting that station to send if it has any traffic to send. See Polling.

Poll Cycle

The complete sequence in which stations are polled on a polled network.

Poll/Final Bit

Bit in HDLC frame control field. If frame is a command, bit is a poll bit asking station to reply. If frame is a response, bit is a final bit identifying last frame in message.

Polling

Connecting to another system to check for things like mail or news. A form of data or fax network arrangement whereby a central computer or fax machine asks each remote location in turn (and very quickly) whether they want to send some information. The purpose is to give each user or each remote data terminal an opportunity to transmit and receive information on a circuit or using facilities which are being shared. Polling is typically used on a multipoint or multidrop line. Polling is done to save money on telephone lines.

Polling Delay

Communications control procedure where a master station systematically invites tributary stations on a multipoint circuit to transmit data. Polling delay is a measure of the time to transmit and receive on a polled network versus a direct point-to- point circuit.

POLSK

POLarization Shift Keying.

Polybutylene Terephthalate

PBT. An insulating material used extensively for buffer tubes which surround optical fibers.

Polyethylene

A family of insulating ( thermoplastic ) materials derived from polymerization of ethylene gas. They are basically pure hydrocarbon resins with excellent dielectric properties. Used extensively in cables.

Polygon

The building block of sophisticated computer graphics.

Polymer

A material having molecules of high molecular weight formed by polymerization of lower molecular weight molecules.

Polymerization

A chemical reaction in which low molecular weight molecules unite with each other to form molecules with higher molecular weights.

Polymorphic Buffer Overflow

PBO is a form of computer attack that experts say will increase on the Internet. PBO works like thus:

1. The worm program containing the PBO attacks a server with a message that's longer than the server expects, causing the system to read the rest of the text as executable code, infecting the computer;

2. Once the worm has infected one server, it scrambles itself before sending itself out to other vulnerable servers. That makes it unrecognizable to the intrusion detection systems designed to look for the worm.

3. When it has infected a new server, it scrambles itself again, and sends itself out to more servers and the process continues. Experts say it will be hard to catch because no worm will look the same.

Polymorphism

The ability of objects to handle different types of information and different requests for actions. Components are not typically polymorphic.

Polyolefin

Any of the polymers and copolymers of the ethylene family of hydrocarbons.

Polypropylene

A thermoplastic similar to polyethylene but stiffer and having a higher softening point (temperature) and excellent electric properties.

Polyvinylchloride

PVC. A thermoplastic material composed of polymers of vinyl chloride. A tough, water and flame-retardant thermoplastic insulation material that is commonly used in the jackets of building cables when fire retardant, but not smoke retardant properties are required. Unfortunately, it burns and gives out noxious gases which kill. PVC can't be run in air return ducts, also called plenum ducts and most towns, therefore, don't allow PVC to be run in their plenum ceilings. See Plenum.

Polyvinylidene Difluoride

PVDF. A fluoropolymer material that is resistant to heat and used in the jackets of plenum cable. See also Plenum Cable.

PON

Passive Optical Network is a fiber optic network without active electronics, such as repeaters, a PON uses passive splitters to deliver signals to multiple terminal devices. Passive optical networking (PON) technology allows a fiber optic network to be built without the costly, active electronics found in all other types of networks. Rather, a PON network relies on inexpensive optical splitters and couplers, which are placed at each fiber "junction," or connection, throughout the network, providing a tremendous fan-out of fiber to a large number of end points. By eliminating the dependence on expensive active network elements ” and the ongoing powering and maintenance costs associated with them ” carriers can realize significant cost savings. (The PON is however still far more expensive than alternatives such as DSL). PON technology generally is used in the local loop to connect customer premises to an all-fiber network. A PON is a tree-like structure consisting of several branches, called Optical Distribution Networks. These run from the central office to the customer premises using a mix of passive branching components, passive optical attenuators and splices. Three active devices can be used in a PON. An Optical Line Terminal (OLT) either generates light signals on its own or takes in SONET signals from a collocated SONET crossconnect. The OLT then broadcasts this traffic to either an Optical Network Unit ONU or an Optical Network Termination, which receives the signal and converts it into an electrical signal for use in the customer premises. The speed of operation depends on whether the PON is symmetrical or asymmetrical. Symmetrical PONs operate at OC-3 speeds (155.52Mbit/sec), for asymmetrical PONs the upstream transmission is also 155.52Mbit/sec from the Optical Network Termination to the customer premises; downstream transmission can range between 155.52 to 622.08Mbit/sec. Depending on where the PON terminates, the system can be described as fiber-to-the-curb (FTTC), fiber-to-the- building (FTTB), or fiber-to-the-home (FTTH). Most PON approaches start with the specifications developed by the Full Service Access Network (FSAN) initiative. Variations on the PON theme include APON (ATM over PON) and TPON (Telephony over PON). See also APON, FSAN, and TPON.

Pond Balls

Golf balls retrieved from a pond or lake.

Pony Express

Out of the summer haze bursts a horse and rider , swiftly approaching a lonely sod building on the prairie. Arriving in a cloud of dust, the rider leaps from his horse and heads for a water barrel to quench his thirst. Meanwhile, a leather sack filled with mail is whisked off the tired horse and thrown over the saddle of a fresh mount. Within two minutes, the rider is gone, galloping toward the far horizon. This young man in a hurry was one of some 200 Pony Express riders who carried the mail in a giant relay between St. Joseph, Missouri, and Sacramento, California, a distance of 1,966 miles, in ten days or less. Changing horses every ten to fifteen miles at swing stations, and switching riders at home stations after a run of 75 miles or more, the riders averaged 250 miles a day. During the short time the Pony Express was in operation ” from April 1860, through October, 1861 ” its rider defied hostile Indians, blazing desert heat, and bone- chilling blizzards to travel a total of 650,000 miles with 34,753 pieces of mail. To save weight the letters they carried were written on tissue -thin paper as postage cost $10 an ounce, later cut to $2. The best time ever achieved was in March 1861, when Lincoln's inaugural address was carried from Missouri to California in seven days, 17 hours.

The Pony Express was organized by stagecoach operator William Hepburn Russell, who had been convinced by a group of prominent Californians that an overland mail route to their state was feasible . Russell's business partners opposed the venture because it was not protected by a U.S. mail contract. (They had competition and de-regulation even in those days.) But Russell went ahead, building stations and purchasing 500 top quality Indian horses. In advertising for riders, he hinted at the hazardous nature of the job by asking for "small, daring young men, preferably orphans." The riders received board and keep and were paid $100 to $150 a month. Their average age was 19, but one rider, David Jay, was 13, and William F. Cody, who became famous as "Buffalo Bill," was 15. In a further effort to save weight, a rider usually carried only a pistol and a knife . He was expected to out-run the Indians, not out-fight them.

The Pony Express days of glory ended abruptly in 1861 following completion of the transcontinental telegraph. Russell's firm lost more than $200,000 in the venture, but the daring of the Pony Express riders caught the imagination of every American, and their exploits became an important part of the legend and lore of the nation. The above history copyright 1979 by Panarizon Publishing Corp.

Ponytail

See Suit.

Ponzi Scheme

A type of scam named after Charles Ponzi, who ran such a scheme in 1919-1920. A Ponzi is somewhat like a pyramid scheme, as money owed early "investors" are paid by revenues collected from those who come later. Typically the scheme works as follows. The Ponzi scheme perpetrator advertises a 50% per year return on monies invested with him. Some monies flow in. At end of a quarter, the perpetrator pays his investors a dividend or return (or whatever he calls it) of 12.5%. Word goes out that he's paid out a handsome dividend. Soon more money flows in. He pays out more dividends. More money flows in. One day not enough money flows in. He can't pay the promised dividends . The whole thing starts to crumble. People start demanding their money back... A Ponzi scheme does not involve any manufacturing of goods, or selling of goods or services.

Poof

The magical successful sending of a computerized form to the next step in the corporate process after all pertinent information has been entered. This definition from a nice reader who works at Verizon.

Pool

A collection of things available to all for the asking or the dialing. A modem pool is a collection of modems typically attached to a PBX. Dial a special extension and you can use the modem, which answers that extension (or one of the extensions in the hunt group) to make a data call. Pooling is sharing. The purpose of having a "pool" is to avoid buying everybody one of whatever it is you're pooling. Actually, "pooling" is a fancy word for something we've been doing in the telephone business for the past 100 years ” sharing. We started sharing lines, then sharing switches, then sharing voice mail devices, now we're sharing equipment, like modems.

Pooling Point

A physical place where local and long distance carriers join their networks in order to swap bandwidth. See Bandwidth Broker.

Pooling Point Administrator

See Bandwidth Broker.

POP

1. Point Of Presence. The IXC equivalent of a local phone company's central office. The POP is a long distance carrier's office in your local community (defined as your LATA). A POP is the place your long distance carrier, called an IntereXchange Carrier (IXC), terminates your long distance lines just before those lines are connected to your local phone company's lines or to your own direct hookup. Each IXC can have multiple POPs within one LATA. All long distance phone connections go through the POPs.

2. Point Of Presence at which ISPs (Internet Service Providers) exchange traffic and routes at Layer 2 (Link Layer) of the OSI model.

3. Short for "population." One "pop" equals one person. In the cellular industry, systems are valued financially based on the population of the market served.

4. Post Office Protocol. An e-mail server protocol used in the Internet. You use POP to get your mail and download it to your PC, using SMTP (Simple Mail Transfer Protocol). POP3 is the current version, as defined in RFC 1725. POP is increasingly being replaced by IMAP.

5. Principles of Operation 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".

POP3

Post Office Protocol version 3 is pronounced "pop three." Think of POP3 as the place in the sky where your incoming email from all your friends is stored, waiting for you to come by and pick it up. All you have to do is to "knock" on your POP3 door, identify yourself and pick up your mail. Conceptually it's not much different from physically picking up mail at your local post office. POP3 is actually a protocol widely used on the Internet or other IP-based networks to retrieve electronic mail from a (typically distant) email server. You use POP3 to get your mail from the server it is sitting on and to download it to your PC. Most email software (sometimes called email clients) use the POP3 protocol. POP3 can be characterized as a store-and-forward mail protocol. It runs on a client/server basis, with your email client workstation (i.e your PC) running against an email server, both of which include POP3 software. POP3 generally makes use of SMTP (Simple Mail Transport Protocol), which is an extension of TCP/IP intended specifically for email transfer. Unlike the earlier POP2 protocol, however, POP3 does not require SMTP and, therefore, is characterized as being independent of the transport layer. POP3 is run by most Internet service providers and ISPs (Internet Service Providers). When accessing a network-based email server, you generally will access a POP3 server to download email. When uploading email, you access an SMTP server, which merely forwards your mail through the Internet after translating the email addresses into IP addresses after consulting with a DNS (Domain Name Server) server. Actually, the two servers may well be in the form of one physical server, logically partitioned into two. So, when I access my main email account at www.TechnologyInvestor.com, using my main email address of [e-mail], I access a local Internet POP (Point Of Presence). I can use a dial up connection through a modem, or DSL (Digital Subscriber Line), or a cable modem network to access the Internet. Anyway is fine. In any event, I run my laptop running the TCP/IP protocol stack and POP3 software against a technologyinvestor.com server running the same software. Once I connect to my server, all of my email downloads immediately, whether I want all of it or not. This all or nothing approach is a major drawback of POP3. If I set up the POP3 options correctly on the client workstation, I can choose to leave a copy of the mail on the server. That way, I can check my email from a friend's or colleague's computer when I'm away from my office, and can still view the mail from my own computer when I get back. POP3 also helps solve the problem of accessing my email when I'm on the road, and outside the local calling areas of my ISP. Let's say I'm in Singapore and I want to check my email. I jump onto the Internet, using any local Internet Service Provider (ISP). I then instruct my email client (in my case, it's Microsoft Outlook.) to go find my technoloyginvestor POP3 email server, the address of which happens to be email.technologyinvestor.com. It finds that server. The server asks me to identify myself by user name and password. Then it starts sending me my email. POP3 is particularly useful because I can pick up my email from wherever I am in the world ” just so long as I can get on the Internet in some way. IMAP (Internet Message Access Protocol) is an improvement on POP3, but is not widely implemented. When you are choosing an email provider, make sure that email provider places your email on a POP3 server and that you can retrieve your email from anywhere. Some companies claim to have "POP3" servers but, for some reason (technical, security or incompetence ), they don't allow you grab your mail over the Internet and download it to your machine. Some email providers insist that you be on line to read and respond to your email. When I wrote an article on the subject of POP3 servers, many readers wrote me that there are "POP3" and "POP3" servers. Thus my warning to check. See also DNS, IMAP, IP, ISP, SMTP, and TCP/IP.

Pop-Under

Also called Pop-Up advertisements. You got to a web site with your browser. You close your browser. Bingo, your taskbar shows your browser has visited another "site" and it's ” surprise, surprise ” an advertisement for a piece of hardware, a cheap airline trip, a lottery, a casino....usually something you don't want. It's called a pop-under because it pops under your browser. It's also very annoying. Companies pay for the privilege of buying these ads. A good piece of software which gets rid of Pop-Unders is called AdsGone and is available from www.AdsGone.com.

Pop-Up

A call center term. A button that displays, on demand, several items from which you can choose (by clicking on it, for example). In effect, this is a list box that you don't see until you push button. Pop-ups always have double lines on their right and bottom sides.

Pop-Up Ad

A typically annoying Web-based advertising technique in which Javascript code creates a small Web browser window that suddenly 'pops up' in the foreground of the visual interface. Pop-ups can contain graphics, HTML, animation, or any combination of the three. Software to prevent pop-ups is available. Our favorite is AdsGone, available from www.AdsGone.com. See Inline ads.

Pop-Up Electronic Mail

An electronic mail system that runs as a terminate-and- stay-resident program (typically within DOS) and can be popped up inside any application to send or read mail. Our office, we have a TSR electronic mail program that pops up. It is called Noteworks and we really love it.

Pop-Up Program

A memory-resident program that is loaded into memory but isn't visible until you press a certain key combination or until a certain event occurs, such as receiving a message. See also TSR.

POPS

A cellular industry term for its customers or its potential customers. (It varies with usage.) POPS, short for "population" (well, sort of) refers to members of the population. According to Ron Schneiderman's book on Wireless, "if the coverage area of a cellular carrier include a popular base of one million people, it is said to have one million POPS. The financial community uses the number of potential users as measuring stick to value cellular carriers."

Populate

The classic definition of "to populate" is to furnish with inhabitants. To populate printed circuit board, you fill it with semiconductors, capacitors and other components. To populate fields in a form, you (or your computer) fill them in.

PORPX

Federal Charge, local number port.

Port

1. noun. The physical interface between a device and a circuit. The device may be a system (e.g., a mainframe, PC, or other host computer), a switch (e.g., PBX, Central Office, or ATM switch) or router, a hub or bridge, a buffer, a printer or other peripheral, or virtually any other type of device. The port and circuit may be either digital or analog, and either electrical (e.g., twisted pair or coaxial cable) or optical (e.g., optical fiber) in nature. The port and circuit connect through some sort of plug and socket arrangement. For example, your PC typically has one or more serial ports and a parallel port.

2. noun. The logical interface between a process or program and a communications or transmission facility. One or more logical ports (Lports) are associated with a single physical port. See also Logical Port

3. noun. A logical point of connection, most especially in the context of TCP (Transmission Control Protocol, which is part of the TCP/IP protocol suite developed for what we now know as the Internet. Port numbers are 16-bit values which range from 0 to 65,536. "Well-known ports" are numbered 0 to 1,023, and assigned by the IANA (Internet Assigned Numbers Authority) for the use of system (root) processes or by programs executed by "privileged users." Examples of well-known ports include 25 for SMTP (Simple Mail Transfer Protocol), 80 for HTTP (HyperText Transport Protocol), and 107 for Remote Telnet Service). In the Internet TCP/IP-based client/server environment the ports are assigned by the server in consideration of the application-level protocol being exercised at the client level. In Internet terms, it is the identifier (16-bit unsigned integer) used by Internet transport protocols to distinguish among multiple simultaneous connections to a single destination host. "Ephemeral ports" are short-lived ports assigned randomly to the source port of the sender, or client. Ephemeral port numbers usually have a value between 1,024 and 5,000. Their short life is due to the fact that the client normally stops using the randomly selected port number once the transaction or session is completed. See also HTTP, IANA, SMTP, TCP, TCP/IP, and Telnet.

4. verb. To move a process, program or subroutine from one processor, controller, or operating system to another. For example, a software developer might "port" an application software system from UNIX to Windows NT.

Port 25 Blocking

ISP use "port 25 blocking" to prevent their subscribers accessing "foreign" SMTP servers, i.e. using other SMTP email servers to send our their mail. The reason? So ISPs can stop their customers spamming . The real reason? To reduce traffic on their network. See Port Services.

Port Address Translation

PAT. A feature which lets you number a LAN (a local area network) with inside local addresses and filter them through one globally routable IP address. Here's an example of when you would use this. Let's say that you have subscribed at your home to a DSL line to the Internet from your local CLEC. For $80 a month you get a line and one IP address. (To get more IP addresses would cost you more money.) You would like to attach several PCs to the line ” your wife's PC, your son's PC, etc. You attach a router to your "digital modem" which your DSL line is terminated on. That router has PAT. It essentially assigns IP addresses behind the DSL. You assign these separate IP addresses to each of your PCs, install cheap Ethernet hubs to joint the PCs together in a LAN and bingo you have a bunch of PCs able to access the Internet. I have exactly this configuration at my home. The device which does the Port Address Translation is a Cisco 1605R router. Companies also use PAT to use one set of IP addresses for internal traffic and a second set of addresses for external traffic. This allows a company to shield internal PCs from the outside world. None of these machines can be reached from the Internet. They can only access the Internet, surf, send email, etc. Port Address Translation is sometimes called Network Address Translation (NAT).

Port Aliasing

Imagine a switch on a local area network. It switches one port to another via a common backplane. We're having trouble and we're looking to do some diagnosis. So we grab all the information flowing through the switch and mirror it (i.e. forward it, but keep it going elsewhere in the switch) to a special port, which we can hook up equipment to and then monitor and check for problems in the resulting data flow ” errors in packets, etc.

Port Connection

The point of entry into a public frame relay network service.

Port Density

The number of ports, physical or logical, per network device.

Port Group

A collection of switch interfaces through which packets can be switched. Port groupings can be distinct for different types of destination addresses: multicast, broadcast, and unicast sprays.

Port Identifier

The identifier assigned by a logical node to represent the point of attachment of a link to that node.

Port Level VLAN

VLAN based on source port ID. This is a multiple bridge configuration of a switch.

Port Multiplier

A local area network interconnect, a concentrator providing connection to a network for multiple devices.

Port Per Pillow

A goal set by colleges seeking to install network connections in the bedrooms of every student on campus.

Port Replicators

Low-cost docking station substitutes that provide one-step connection to multiple desktop devices.

Port Scanning

Port scanning is the technique of attempting to find listening TCP or UDP ports on an IP device and abstracting from the listening ports as much information as possible about the device. Port scanning in and of itself is not usually harmful but it lets potential crackers fingerprint your systems, learn everything they can about your possible vulnerabilities and set themselves up for a later intrusion. For example, if a port scan shows that the device is listening on port 23, the cracker knows that Telnet is likely enabled on the device and can attempt a brute force password guessing attack later.

Port Selector

Another name for a dataPBX. Since the advent of LANs (local area networks) these devices have been getting a bad rap. Not fair. These gadgets are really great at transmitting and switching huge number of low-speed asynchronous lines. If you put this sort of traffic on a LAN, you could severely mess up its performance. Some port selectors have data throughput in excess of 20 million bits per second.

Port Services

Servers attached to the Internet run software for various purposes ” sending mail, receiving mail, publishing web pages, etc. In Internet-speak, these software programs are called "port services." RFC's (Request for Comments) define the nature of the service and standard TCP/UDP port assignments. For example SMTP (Simple Mail Transfer Protocol) is nominally run on port 25, and POP3 (Post Office Protocol version 3) is located on port 110. Typically, organizations run these services behind a firewall. A firewall is designed to keep unwanted intruders out. Because these servers are enticing targets for unethical hackers, these people often run software across the Internet designed to see if they can penetrate into these servers and cause damage, or find secrets (like email addresses, credit card numbers). These are called " intrusive scans ." Most intrusions begin with a port scan, a sequential query of available ports and services on an exposed system. Most firewalls will keep track of these attempts by hackers and capture the IP address of the system doing the scanning. A network administrator can then use this information along with a network trace utility such as traceroute to identify the originating ISP. Once that is found, the network administrator and a representative of the source ISP can typically find the hacker and suggest to him/her that she lay off. Thank you to Matt Kalas of Telephone@Work for help on this definition.

Port Sharing

1. A system which connects multiple lines to a single port by means of a manual or automatic line selection method.

2. In frame relay, where multiple virtual connections share the same port connection.

Port Sharing Device

A system which connects multiple lines to a single port by means of a manual or automatic line selection method.

Port Switching

According to 3Com, port switching is merely an electronic patch panel function, not the genuine switching capability that provides a performance boost. Port switching lets administrators configure their networks, allocating any port to any backplane on their hub. Unlike true switching, it doesn't increase the bandwidth available to the network manager.

Portability

1. The ability of a customer to take his telephone number from place to place and, for 800 numbers, from one long-distance company to another.

2. The ability of software designed for one computer system to be used on other systems. Little software outside MS-DOS software for IBM and IBM clone computers is portable. UNIX software is portable to an extent.

Portable

A one-piece, self-contained cellular telephone ” easily carried in a brief case or purse. Portables normally have a built-in antenna and rechargeable battery and operate with six-tenths of one watt (0.6 watt) of power. Car cellular phones operate with three watts.

Portable Application Description

See PAD.

Portable Cellular Phone

Also known as a "hand-held phone". Refers to a lightweight, compact cellular handset that incorporates a battery power supply, and can be used without any peripheral power or antenna. See Portable.

Portable Teletransaction Computers

PTC. These are typically hand- held 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.

Portable NXX

A Verizon definition. An NXX from which at least one number has ported or there is a pending order to port a telephone number.

Portal Site

The classic definition of a portal is a door, gate, or entrance , especially one of imposing appearance, as to a palace. In the Internet / World Wide Web, a portal is a site, which the owner positions (through marketing and heavy promotion) as an entrance to other sites on the Internet. The concept is that he convinces visitors to the Internet to visit his site first, and savor the advertising on his site (his major way of making money). A portal typically has, at minimum, search engines, free email, instant messaging and chat, personalized home pages and Web hosting. In the past, companies like America Online and CompuServe would have been called portals. Many browsers (e.g., Netscape Navigator and Internet Explorer) point you to a Web site ” their own Web site, which they are endeavoring to position as a "portal." Once there, you might then want to use a search engine (e.g., AltaVista, Excite, Infoseek, Lycos, Yahoo). You are then taken to their Web site. These sites serve as your secondary portal, or point of entry, into the Web. At each of these Web sites you are assailed with advertisements. Also, cookies are embedded in your computer so they can track your movement and activities on the Web to get a feel for your viewing and buying preferences and, ultimately, develop a profile on you for purposes of targeted on-line advertising. You can change your initial portal, if you like, perhaps pointing your browser to the Web site of favorite financial information provider (e.g. Bloomberg or Nasdaq), rather than that of Netscape or Internet Explorer. Portals are BIG business. In July 1998, Walt Disney Co. offered $900 million for 43 percent interest in Infoseek, a 4-year old startup with fewer than 200 employees and annual sales of about $35 million. At the time, Infoseek had never made a profit. See also Portal Service.

Portal Service

First, read my definition for Portal above. Then add these words. Portal Service is a whole architectural concept surrounding and including a point of entry. Portal Service introduces the concept of service on which other Internet services could be built. Such services provide an entry point on which other applications and services can be built, customized and enhanced to suit an envisaged deployment of any new services via a library of building blocks.

Ported In A Verizon definition. A telephone number is considered to be ported in when service provider A provides service in their switch with a telephone number assigned to service provider B's switch using local routing number (LRN) technology.

Ported Out

A Verizon definition. A telephone number is considered to be ported out when a number assigned to service provider A is moved from service provider A's switch to service provider B's switch, using local routing number (LRN) technology.

Portrait

Most computer screens are horizontal, i.e. they are wider than they are high. In the new language of computer screens, this is called "landscape." When a computer screen is higher than it is wide, it's called "portrait." Some computer screens can actually work both ways. Some even have a small mercury switch in them that determines which way the screen is standing (portrait or landscape) and will adjust their image accordingly, though software in the computer has to reflow the image. See also Portrait Mode.

Portrait Mode

1. In facsimile, the mode of scanning lines across the shorter dimension of a rectangular original. ITU-T Group 1, 2 and 3 facsimile machines use portrait mode.

2. In computer graphics, the orientation of a page in which the shorter dimension is horizontal. The opposite is called landscape mode. See also Portrait.

POS

1. Point Of Service. Also called Point of Presence. See Point of Presence.

2. POS Device. A point of sale device such as a credit card scanner used for authorization when a purchase is made.

3. Packet Over SONET. A high-speed means of transmitting data over a SONET fiber optic transmission system through a direct fiber connection to a data switch or router. POS is a point-to-point, dedicated leased-line approach intended purely for high-speed data applications. Where a point-to-point approach is possible, POS offers significant advantages when compared to ATM's cell-switching approach. Specifically, POS allows a user organization to pass data in its native format, without the addition of any significant level of overhead in the form of signaling and control information. For example, POS allows Ethernet frames to be packed into STS-1 (Synchronous Transport Signal-1) frames of 810 bytes, with only 36 bytes of overhead- an overhead factor of less than 1% ” and then sent over an OC-1 (Optical Carrier-1) frame at 51.84 Mbps. For higher capacity applications, SONET supports example rates of approximately 155 Mbps, 622 Mbps, 2.4 Gbps and 10 Gbpsall with the same low level of overhead, or inefficiency. ATM, on the other hand, is a cell- switching approach that segments each data frame into small cells of 53 octets, of which 5 octets are overhead-an inefficiency, or overhead, factor of approximately 11% ATM, on the other hand, will support voice, video, fax and any other form of traffic, as well as true data traffic.

4. Personal Operating Space. As defined by the IEEE 802.15 Working Group, which is engaged in the development of WPAN (Wireless Personal Area Network) standards, the POS covers a range of 10 meters. Within that space, low power, low data rate WPAN technologies can operated on a fixed, portable or mobile basis. See also 802.15.

POS-PHY

Packet Over SONET-PHYsical layer. A specification for Packet over SONET, with SONET running at the Physical Layer (Layer 1) of the OSI Reference Model. See also OSI Reference Model, SONET, and POS.

POSI

Promoting Conference for OSI. Consists of executives from the six major Japanese computer manufacturers and Nippon Telegraph and Telephone. They set policies and commit resources to promote OSI.

Position

A telephone console at a switchboard manned, oops, staffed by an attendant, or operator, or agent, or whatever the latest PC-correct word is.

Position Calculation Method

The location estimate is performed by a Position Calculation Function (PCF) located in the network or, if the MS has the capability, in the MS itself. With the same network architecture, MS functions, LMU functions and measurement inputs, the PCF can be based on one of two possible variants of E-OTD; known as 'circular' and ' hyperbolic '. See Position Determination Technology and Location Services.

Position Determination Technology

PDT. also known as Geolocation Technology. A technology used to determine the geographic coordinates of a radio- equipped mobile device, e.g., a cellular handset. Generally refers to technology that allows the device's position to be monitored remotely, such as by an emergency service operator in the case of a wireless E-911 call. "Position" is preferred in some circles to avoid confusion with the use of "location" in reference to cellular system roaming. Three general classes of PDT are as follows.

• Network-based. Fixed-site network infrastructure (e.g., collocated or consolidated with the cellular base station) determines device's position based on received signal measurements. Includes Angle of Arrival and Time Difference of Arrival technologies. See Angle of Arrival.

• Handset-based. The mobile device determines its own position (e.g., from an integral Global Positioning System receiver) and reports it to the network.

• Handset-assisted. A hybrid approach wherein the mobile device collects some measurements from its environment that are reported to the network infrastructure which in turn uses them to derive the mobile's position. See also Position Calculation Method and Location Services.

Positive Action Digit

A digit that must be dialed before a PBX will advance a call to a higher-cost route. The WATS lines are busy. Time on the queue is over. It's time to move the call to the more expensive direct distance dial. Before it can go that route, the caller must punch in a positive action digit. This affirms that the user knows he is now making a more expensive call. It causes him to think twice, allegedly.

Positive Trapping

Use of a notch filter to trap out an interfering carrier inserted in the channel in order to deny service to non-subscribers.

POSIX

Portable Operating System Interface uniX. A proposed universal UNIX interface to user-created application programs that would run on all vendor equipment, thereby improving system interoperability.

Post

1. 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.

2. To compose a message for an Internet Usenet newsgroup and then send it out for others to see.

3. Power-On Self-Test.

Post Bubble Anxiety Disorder

PBAD. Financial worries caused by the economic chaos that followed the dotcom boom. A Slate writer remarked that PBAD even afflicts characters in The Sopranos. "The fact that (Tony) has money worries ” aggravated by Carmela's post-bubble anxiety disorder ” only makes the problem worse ."

Post Completion Discrepancy

PCD. A service order request that fails the billing system edits.

Post Dial Delay

PDD. The time from when the last digit is dialed to the moment the phone rings at the receiving location.

Post Office

Any part of an email system that stores or delivers mail. the term post office needs a modifier. A local post office or host post office is the module on a network that users directly interact with to send and receive mail. A domain post office is the module that controls the mail delivery within a domain of multiple hosts on a single network. For a full explanation, see POP3.

Post Office Act

In 1969, in the U.K. this act began the process of removing telecommunications from direct government control. See also the British Telecommunications Act.

Post Office Protocol

See POP3.

Post Pay

A method of coin phone operation characterized by the operation of a lever or button that causes the collection of deposits after the called party answers. This method of "A" and "Buttons" is still used on coin phones overseas, especially in Great Britain.

Post Production

The editing process after the video footage has been shot.

Post Restante Address

A standard attribute in a postal address indicating that physical delivery at the counter is requested. It may also carry a code.

Post Tensioned Concrete

A type of reinforced concrete construction in which the steel is put under tension and the concrete under compression, after the concrete has hardened .

Post-it Note

A scientist at the 3M laboratory, Dr Spence Silver, didn't know what to do with a failed glue he developed. The thing wouldn't stick, except for a short period of time. His colleague Art Fry, remembering how annoying it was to have little bits of paper marking pages in his music book fall out during choir practice, had a suggestion for temporary adhesive book marks. Other co-workers started using strips of paper coated with the glue to write notes. Today, Post-it notes are among the five top-selling office products.

Post-mortem Divorce

A stipulation that one must be buried separately from one's deceased spouse.

Postage

Money paid for conveyance by mail. Mailing a building has been illegal in the U.S. since 1916, when a man mailed a 40,000-brick house across Utah to avoid high freight charges.

Postal Telephone and Telegraph

PTT. The official government body that administers and manages the telecommunications systems in many European countries .

Postalize

To structure rates or prices so that they do not vary with the distance you're speaking, but depend on other factors (such as duration of a call, etc.) See also Postalized.

Postalized

Long distance phone calls were traditionally billed based on a costing algorithm which considered the distance between the originating and terminating points, call duration, and time of day. U.S. carriers, for the most part, currently no longer consider distance in the costing algorithm for domestic calls. In other words, long distance calls are subject to "postalized" charging ” from the fact that Post Office also charges a flat rate irrespective of how far it carries the mail (within the country). Charges for circuit- switched data calls (e.g., Switched 56/64 Kbps), for the most part, also are postalized.

Postalized Rates

Refers to the way the post office prices their delivery services, namely one price to anywhere in the United States. See Postalized.

Posting

An individual article sent to a USENET news group on Internet; or the act of sending an article to a USENET news group.

Postlink

A program used by a RIME bulletin board system node in place of mailer software.

Postmaster

A postmaster could be the person responsible for taking care of mail problems, answering queries about users, and performing similar work for a given site. It could also be an alias for a mail server (i.e. computer) for routing and handling of electronic mail within an organization.

Postmortem Divorce

A phenomenon among Japanese women who, unhappy in their marriages, secretly arrange to have themselves buried anywhere but beside their husbands.

Postoffice

See Post Office.

Postpay

See Post Pay.

Postscript

1. PostScript is a popular format used to create World Wide Web screens and send documents over the Internet.

2. PostScript by Adobe Systems Inc. is the standard page description language for desktop computer systems. It describes type, graphics and halftones as well as the placement of each on the page. The big advantage of PostScript is that it is device independent. Thus if you create a postscript image (text and/or photo and/or drawing), you can print it to a relatively cheap, low quality printer like a laser printer or a magazine quality printer like a Linotronics. PostScript is a printer language, much the same that BASIC is a computer language. By sending your PostScript printer a series of commands, you can make it do almost anything from printing text in a circle to printing foot -high letters to printing halftones . If you need PostScript, buy a printer that has built-in PostScript. If your printer doesn't have built-in PostScript, you may be able to get an external software interpreter but that interpreter will slow down your printer and tie up your computer while printing. Recent versions incorporate Adobe's Portable Document Format (PDF), a popular file format designed to allow everybody to read or view files even if they don't have the software the files were created with. The program used to read these files is called Adobe Acrobat, and is freely available on the Web, but you have to purchase the full-version Acrobat to create, modify and add notes to PDF files. You can convert Postscript files (which can be identified by their ".ps" extension) to PDF files (which have a ".pdf" extension) using Acrobat. PostScript first appeared in 1985, and grew out of a programming language called Interpress that Adobe's founders, John Warnock and Chuck Geschke developed while working at Xerox's Palo Alto Research Center (PARC). See also Acrobat, PDF, PARC.

POT

1. Techie-slang for potentiometer.

2. Point Of Termination. The point of demarcation within a customer designated premises at which the telephone company's responsibility for the provision of access service ends.

POT Bay

The POT Bay, or Point-Of-Termination bay, is a device placed between a competitor's network and the natural point of connection to the local exchange carrier (LEC) network. It is located between a LEC's main distribution frame (MDF), which directs traffic to proper channels for distribution throughout the LEC network and the interconnector's colocated equipment. The POT Bay, according to most new local phone companies (i.e. ones that are not a Bell operating company), is an unnecessary obstacle that adds to the costs of interconnection, serves no necessary engineering function, can degrade quality, and is nothing more than a latter-day "protective coupling arrangement."

Potato

1. Also called Aerial Service Wire Splice. A tool used to splice aerial service wire.

2. When potatoes were first brought to Europe in the 17th century, they were considered disgusting and blamed for starting outbreaks of leprosy and syphilis. As late as 1720, in America, eating potatoes was believed to shorten a person's life. Potatoes were banned in Burgundy, France in 1910. Fortunately that madness didn't last long and Burgundy now sports many McDonalds' restaurants .

Potemkin Village

In 1787, Catherine the Great tours Crimea and other lands newly taken from Turks. The problem was that war had ravaged the areas. But when the Empress is in the areas, she sees only apparently prosperous villages. These villages, however, were in fact were mere facades erected by her principal adviser (and lover), Prince Grigori Aleksandrovich Potemkin. He put them up to fool her into believing in the great progress of the New Russia. Potemkin Village now means pretentious fakery.

Potential

The difference in voltage between one point and another. One point is usually ground.

Potential Revenue

A call center term. The revenue value per call times the number of calls forecast for a given period.

Potentiometer

A variable RESISTOR, such as the ubiquitous volume control.

Potting

In many European countries, the local regulatory authorities are very strict about voice boards that are attached to phone lines. Because phone lines have high voltage for ringing ” 90 volts AC and higher ” the authorities feel that the phone lines may caused an electrical short and possibly a fire. As a result, the authorities insist that the area of the voice boards which receives the high voltage be covered with some protective non- flammable material. Covering your board is called potting.

POTS

Plain Old Telephone Service. Pronounced POTS, like in pots and pans. The basic service supplying standard single line telephones, telephone lines and access to the public switched network. Nothing fancy. No added features. Just receive and place calls. Nothing like Call Waiting or Call Forwarding. They are not POTS services. All POTS lines work on loop start signaling. See also Loop Start.

POTS Splitter

A device that rejects the DSL signal and allows the POTS frequencies to pass through.

POTS-C

Plain Old Telephone Service-Centralized. An ADSL term for the functional interface between the PSTN (Public Switched Telephone Network) and the POTS splitter at the Centralized (i.e., Central Office) end of the network. The POTS splitter is a filter that uses FDM (Frequency Division Multiplexing) to separate the low-frequency POTS voice channel from the high-frequency ADSL data channel. See also POTS-R, ADSL, FDM and Splitter.

POTS-R

Plain Old Telephone Service-Remote. An ADSL term for the functional interface between the POTS splitter at the Remote (i.e., customer premise) end of the network and the individual telephone sets on premise . The POTS splitter is a filter that uses FDM (Frequency Division Multiplexing) to separate the low-frequency POTS voice channel from the high-frequency ADSL data channel. See also POTS-C, ADSL, FDM and Splitter.

POTV

Plain Old TV. A Microsoft definition. I kid you not.

Pound

The # on a pushbutton touchtone key pad is called the pound key. It's also called the number sign, the crosshatch sign, the tic-tack-toe sign, the enter key, the octothorpe (also spelled octathorp) and the hash. Musicians call the # sign a "sharp." See also # in the numbers section at the beginning of this dictionary.

Pound Key

See Pound.

Pound Sand

To pound sand means to act ineffectively, to waste time and accomplish nothing. Think about hitting sand with a baseball. Now you understand the meaning.

Power

The term which describes the amount of work an electric current can do in a unit of time. We measure power in WATTS (note we spell it with two "T"s.) A WATT measures the amount of work done in lifting a quarter-pound weight a distance of one yard in one second. Metric WATTS are a little more powerful. They go the distance of one meter. Power is the product of the current in amperes times the voltage, i.e. P = IV. See Ohm's Law.

Power Budget

In fiber optic cable communications, power budget is the difference between the transmitted power and the receiver sensitivity, measured in decibels. It is the minimum transmitter power and receiver sensitivity needed for a signal to be sent and received intact.

Power Carrot

A term for a mobile phone in Japan that does nothing more than receive and transmit phone calls.

Power Conditioner

A combination voltage regulating transformer and isolation transformer, providing smooth, regulated , noise-free, AC voltage. See Power Conditioning.

Power Conditioning

Power conditioning is a generic concept to encompass all the methods of protecting sensitive hardware against power fluctuations. When electricity leaves a commercial power generating plant, it is very clean. In fact, most power companies make sure the power they put out is a pure sine wave. Unfortunately, nearly all devices connected to power lines ” and the worst are things with motors, like elevators, air conditioners, etc. ” create disturbances that pollute the sine wave. As power travels through a wire away from the power plant, it picks up more of these interferences . A pure AC power sine wave appears as a smooth wave. The height of the wave is measured in volts. The wave starts at zero volts and moves to the highest point of 120 volts. The wave then cycles through a low point of -120 volts and back to zero. The speed at which it travels through this cycle is the frequency. Normal frequency in North America is 60 cycles per second (Hz). (In other places it's often 50 cycles per second.) Anything that disrupts this wave can cause hardware or data problems and needs to be regulated.

Power disturbances can be categorized in several ways. A transient, sometimes called a spike or surge, is a very short, but extreme, burst of voltage. Noise or static is a smaller change in voltage. Brownouts and blackouts are the temporary drop in or loss of electrical power. Three types of protection against these three events are available: suppression, isolation, and regulation.

Suppression protects against transients. The most common suppression devices are surge protectors that include circuitry to prevent excess voltage. Although manufacturers originally designed surge protectors to prevent large voltage changes, most have also added circuitry to reduce noise on the line. Isolation protects against noise. Ferro-resonant isolation transformers use a transformer within the circuitry to envelop the sine wave at a slightly higher and lower voltage. Any voltage irregularity that extends beyond this envelope is clamped. Isolation transformers are usually expensive.

Regulation protects against brownouts and blackouts. Regulation modifies the power wave to conform to a nearly pure wave form. The Uninterruptible Power Supply (UPS) is the most commonly used form of regulation. A UPS comes in two varieties, on-line and off- line. An on-line UPS actively modifies the power as it moves through the unit. This is closer to true regulation than the off-line variety. If a power outage occurs, the unit is already active and continues to provide power. The on-line UPS is usually more expensive but provides a nearly constant source of energy during power outages. The off-line UPS monitors the AC line. When power drops , the UPS is activated. The drawback to this method is the slight lag before the off-line UPS jumps into action. That lag is getting shorter as electronics improves. So it's rarely a problem any longer.

Because UPS systems are expensive, most companies attach them only to the most critical devices, such as phone systems, network file servers, routers, and hard disk subsystems. Attaching a UPS to a local area network file server enables the server to properly close files and rewrite the system directory to disk. Sadly, most programs run on the workstation and data stored in their RAM is not saved during a power outage unless each workstation has its own UPS. If the UPS doesn't have its own form of surge protection, it is a good idea to install a surge protector to protect the UPS from transients. Proper use of power conditioning devices greatly reduces telephone system and network maintenance costs. Make sure that proper amperage is available for each system and that all outlets are grounded. Power conditioning devices connected to poorly-grounded outlets offer very little protection.

Studies have shown that total local area network maintenance costs are higher with line-surge suppressors and ferro-resonant isolation transformers alone, than with uninterruptible power supplies.

Power Conditioning Systems

A broad class of equipment that includes filters, isolation transformers, and voltage regulators. Generally, these types of equipment offer no protection against power outages.

Power Cross

A situation in which AC current flows into a telephone circuit, as a result of contact with a power line.

Power Cycle

Power cycle means the same as reboot. See Reboot.

Power Density

Power per unit area normal to the direction of propagation, typically expressed in units of watts per square meter (W/m2) or microwatts per square centimeter (W/cm2).

Power Dialer

A piece of hardware to which you feed a list of phone numbers you want called. It calls them one after another. It detects busies, no answers, fax machines, answering machines, voice mail machines, etc. When it hears these, it disconnects and dials the next number in the list. If it reaches a live human being, it will pass the call to the owner of the machine, who will presumably try and sell the fellow at the other end something, or try and collect money from him ” the two main uses which power dialers are typically put to. The term "power dialer" is fairly new. I first saw it used on a single line device. It seemed to need a prompt from its owner to dial the next call, very much like a preview dialer. See also Predictive Dialing and Preview Dialer.

Power Distribution Panel

A part of the Rolm CBX power distribution system that receives voltages from the main power supply and distributes them to the cabinet shelves .

Power Divider

A splitter which divides power from a single input into two isolated outputs. Devices with more than two outputs can also be found.

Power Down

The sequence of things you to have to do to turn off a computer or telephone system. Not following the correct power down procedures can cause a loss of data.

Power Factor

This is a number between 0 and 1 which represents the portion of the VA (Volt-Amps rating) delivered to the AC load which actually delivers energy to the AC load. With some equipment such as motors or computers, AMPS flow into the equipment without being usefully converted to energy. This happens if the current is distorted (has harmonics) or if the current is not in phase with the voltage applied to the equipment. Computers draw harmonic currents which cause their power factor to be less than 1. Motors draw out of phase or reactive currents that cause their power factor to be less than 1. See also VA. This definition courtesy American Power Company.

Power Factor Corrected Supply

PFC. A recently developed type of computer power supply, which exhibits an input power factor equal to one. IEC555 may force most computers to use a power supply of this type at some point in the future.

Power Fail Bypass

A feature that allows analog trunks to be answered if your commercial AC power or your telephone system crashes.

Power Failure Backup

If your AC power fails, your telephone system can still operate by switching to a backup battery power supply, often called a UPS ” Uninterruptible Power Supply.

Power Failure Transfer

When the commercial AC power fails and there is no backup power source ” such as a battery or a generator ” this feature switches some of the trunks connected to the phone system to several single line phones, which don't need external power and can draw their power from the phone lines.

Power Frequency

Power frequency is the term used to describe the frequency of the alternating current wave that we use for electricity. Power-frequency fields in the US vary 60 times per second (60 Hz), and have a wavelength of 5,000 km. Power in most of the rest of the world is 50 Hz, i.e. 50 times a second.

Power Influence

1. Power influence refers to AC electrical pollution currents. This is when AC electrical power currents induce voltage along the wires of a pair, looking for paths to ground and because they are noise currents, they are also referred to as "Noise to Ground". These currents are residual currents that are not canceled out by a cable's bonding and grounding system. These left over currents cause noise on a pair and are measured by using a Power Influence meter. Power Influence is measured from tip and ring to ground. Typical values for power influence range from below 60dBrnc to more than 100dBrnc. The higher the power influence value, the more noise that is heard in the telephone receiver. These values are used to determine the circuit balance of a telephone circuit by using the formula: Circuit Balance = Power Influence - Circuit Noise.

2. A Verizon definition. The power of a longitudinal signal induced in a metallic OSP facility by an electromagnetic field emanating from a conductor or conductors of a power system. PI is also called longitudinal noise or noise-to-ground.

Power Level

The measure of signal power at some point. The measure can be referenced to some power level in which case the measurement is expressed in dB (decibels). It may also be referenced to 1 milliwatt in which case the measurement is expressed in dBm.

Power Line Carrier

PLC. An AC power line can be made to carry high frequency radio waves, which can carry "information," which could be a voice or data call. Over the years many companies have tried power line carrier ” a seductively easy method of not having to install conventional phone lines. The results have been poor-to- awful . For example, rural telephone companies once made use of PLC in order to serve very remote farms and ranches over power lines run the local power utilities. The power utilities, themselves, still make extensive use of PLC as a backup for more conventional copper and microwave transmission systems. A number of manufacturers over the years have developed residential and small business telephone systems which use in-building AC power. The telephone line is terminated by special equipment at the common electrical bus, with the individual sets simply plugging into electrical outlets like a toaster or any other electrical appliance. (Do not confuse this odd approach with the term "Information Appliance," which refers to multipurpose, multimedia terminals used in a convergence (Information Superhighway) context.) Such systems have not been successful.

Recently, several technical developments have resurrected interest in PLC. First, Spread Spectrum technology has been applied to overcome the inherent noise problems associated with data communications over in-building electrical wiring. Second, the EIA's (Electronic Industries Association) CEBus (Consumer Electronics Bus) was adopted industrywide. CEBus essentially is a Home Area Network (HAN), a residential and small business version of a Local Area Network; CEBus makes use of Spread Spectrum. Current commercial PLC applications using Spread Spectrum include control of building environments and managing utility electrical distribution systems. For instance, heating, ventilation , and air-conditioning systems in a commercial building can be managed by a central controller which polls various temperature and humidity sensors scattered throughout the building with communications taking place over the electrical wiring and through the common electrical bus. See Spread Spectrum and CEBus.