Airdome Control Station-Apocalypse, Four Horsemen Of

Airdome Control Station-Apocalypse, Four Horsemen Of

Airdrome Control Station

An aeronautical station providing communication between an airdrome control tower and aircraft. Also called airport control station.


Additive Increase Rate Factor: Refer to AIR.

Airline Control Protocol

Data link layer polled protocol that runs in full-duplex mode over synchronous serial (V.24) lines and uses the binary-coded decimal (BCD) character set.

Airline Mileage

The monthly charge for many leased circuits is billed on the basis of "airline mileage" between the two points. Though it sounds as if it's the distance a crow would fly directly between the two points, in reality, it is the distance in mileage between two Rate Centers whose position is laid down according to industry standards, originally created by AT&T. The entire U.S. is divided by a vertical and horizontal grid. The coordinates ” vertical and horizontal ” of each rate center are defined and applied to a square root formula which yields the distance between the two points. Think back to school. There's a right-angled triangle. At the top is one Rate Center. At the side is the other Rate Center. The horizontal is the horizontal coordinate. The vertical is the vertical coordinate. The formula is simple: Square the vertical distance. Square the horizontal distance. Add the two together. Then take their square root. That will give you the distance across the hypotenuse ” the side opposite the right angle in the triangle. Thus, your "airline" mileage. For sample V and H city coordinates and the formula on how to calculate airline mileage, see V & H under the letter V.

Airline Miles

See Airline Mileage.

Airline Protocol

Generic term that refers to the airline reservation system data and the protocols, such as P1024B (ALC), P1024C (UTS), and MATIP, that transport the data between the mainframe and the ASCUs.

Airline X.25

See AX.25.


A cellular radio term. Airlink is the physical layer radio frequency channel pair used for communication between the Mobile End System (M-ES) and the Mobile Data Base Station (MDBS).

Airlink Interface

The Cellular Digital Pack Data (CDPD)-based wireless packet data service provider's interface for providing services over the airlink to mobile subscribers.


Actual time spent talking on a cellular telephone. Most cellular carriers bill their customers based on how many minutes of airtime they use each month. Whether the calls are incoming or outgoing makes no difference, the customer is still billed. Whether the calls are going to a toll-number or a toll-free 800 number also makes no difference. The customer racks up airtime and he pays. The more minutes of time spent talking on the phone, the higher the bill. Airtime charges during peak periods of the day in North America vary from 25 to 80 cents per minute. Most carriers offer a discount on these rates for off-peak usage. Some carriers offer a discount on these rates if the customer pays a higher minimum usage charge each month.


Airwave systems are transmission systems that use the "airwaves," rather than conductors, to transmit information. Airwave systems actually send information across "space," rather than through conductors. The term "airwave" comes from the fact that human speech, in its native form, is an acoustic means of communications which makes use of the physical matter in the air to conduct compression waves. From mouth (transmitter) to ear (receiver) the physical matter (e.g., molecules of oxygen , carbon dioxide and such) in the air actually carries, or conducts, the signal. Airwave transmission systems (e.g., microwave, satellite and infrared) support information transfer from transmitter to receiver through space, using electromagnetic energy in the form of radio or light signals. The presence of the physical matter which occupies the space between transmitter and receiver actually causes the signal to attenuate, or weaken. The term "airwave" persists, however. See also Free Space Communications.


  1. Alarm Indication Signal. Formerly called a "Blue Alarm" or "Blue Signal." An AIS is a signal transmitted downstream informing that an upstream failure has been detected . AIS is a signal that replaces the normal traffic signal when a maintenance alarm indication has been activated. In ATM, an alarm indication signal is an all ones signal sent down or up stream by a device when it detects an error condition or receives an error condition or receives an error notification from another unit in the transmission path . See also Squelching.

  2. Automatic Intercept System.

  3. Automated Information System. Any equipment of an interconnected system or subsystems of equipment that is used in the automatic acquisition, storage, manipulation, control, display, transmission, or reception of data and includes software, firmware, and hardware.


Association of Information Professionals. AITP began life in 1951 as the NMAA (National Machine Accountants Association), changed its name to the DPMA (Data Processing Management Association) in 1962, and then to AITP in 1996. AITP provides IT- related education, information on relevant IT issues, and forums for networking with peers.


Application Implementer's Workshop. A group of vendors working with IBM to develop software and hardware consistent IBM's Advanced Peer-to-Peer Networking protocol.


Advanced Interactive eXecutive: IBM's implementation of UNIX. The Open Software Foundation (OSF) based its first operating system (OSF-1) on AIX. The next revision of the OSF operation system (OSF-2) will also be based on AIX with a Mach kernel (Mach was developed by Carnegie Mellon University).


Bisync acknowledgment for even-numbered message.

Aka Denwa

Japanese for a red telephone. Some coin phones in Japan are red and are known as aka denwas.


ATM Adaptation Layer. The third layer of the ATM Protocol Reference Model. The AAL layer comprises the Convergence Sublayer (CS) and the Segmentation and Reassembly sublayer (SAR). In total, it is at this layer that multiple applications are converted to and from the ATM cell format. ATM Adaptation Layer sits above the ATM Layer, supporting higher-layer service requirements. For data communications services, the AAL defines a segmentation/reassembly protocol for mapping large data packets into the 48-octet payload field of an ATM cell . See the next the five definitions. See also CS AND SAR.


AppleTalk Link Access Protocol. In an AppleTalk network, this link access-layer (or data link-layer ) protocol governs packet transmission on LocalTalk.


Notification that the traffic signal has degraded or failed or equipment is malfunctioning. An SNMP message notifying an operator or an administrator of a network problem. See also Event and Trap.

Alarm Display

  1. A message notifying an operator or administrator of a network problem.

  2. Attendant console indicators show the status (i.e. what's happening) in the telephone system. There are usually two types of alarms ” minor and major. Minor displays may be something as "minor" as a "hung" trunk, i.e. one that didn't hang up when the person speaking on it hung up. They can often be remedied by turning the PBX off, counting to ten, and then turning it on. (Before you do, check it will load itself.) Major problems ” such as a blown line card in the PBX, one console out or half the trunks out ” often require a service call and are often covered under the Emergency Conditions section of telephone service contracts.

Alarm Holdoff

See Alarm Soaking.

Alarm Indication Signal

AIS. A signal that replaces the normal traffic signal when a maintenance alarm indication has been activated. See the next definition.

Alarm Indicating Signal

AIS. Also known as a "Blue Alarm Signal" or "All Ones Keep Alive," an AIS is an unframed all-ones bit pattern sent by equipment at the far end to indicate that an alarm condition exists upstream in a circuit leading to the downstream equipment. Keep- alive signals are required by the network facilities to prevent oscillation of the line repeaters which causes interference (i.e. cross-talk and bleeding) within adjacent channels. SONET defines four categories of AIS: Line AIS, STS Path AIS, VT Path AIS, DSn AIS.

Alarm Soaking

The allowing of an error condition to persist before action is taken. Alarm holdoff is another term for it. The term "soak period" is used for the holdoff period.


Analog Loop Back. A test to see if a phone line is working and how well it's working. Analog Loop Back is a common test for locating transmission problems in data transmission systems.


Many Japanese golfers carry "hole-in-one" insurance. With the Japanese, who take their golf very seriously, it is traditional to share one's good luck by sending gifts to all your friends when you get an "ace." The cost of what the Japanese term an "albatross" often reaches $10,000. See Albatross Manager.

Albatross Manager

He hangs around you constantly. You can't get rid of him. This definition courtesy Tom Henderson. See also Seagull Manager.


Automatic Line BuildOut. ALBO is a means of automatic cable equalization used in T-1 span-line interface equipment.


  1. Automatic Level Control.

  2. See Automatic Light Control.

  3. Airline Line Control. A full-duplex, synchronous communications protocol used in airline reservations systems. ALC is a packet polling protocol which adheres to a strict master/slave relationship between the central host and the remote terminals. ALC relies on IBM's IPARS (International Airline Passenger Reservation System) character set, which comprises 6 data bits and no parity bits. Error detection is accomplished through a Cyclic Check Character (CCC), but only very limited procedures are identified for error correction. ALC was designed for use in X.25 networks, but also works in a Frame Relay environment.

  4. Assembler Language Coding.


Alcatel is a huge French telecommunications manufacturer. Its real name is Compagnie Alcatel. And it's based in Paris. Lucky company.


  1. Approvals Liaison Engineer. This engineer acts on your behalf to assess design and component changes to your BABT approved products. BABT is the British Approvals Board for Telecommunications.

  2. See Automatic Link Establishment.

  3. Access Line Equipment.

Alerter Service

A Windows 2000 term. Notifies selected users and computers of administrative alerts that occur on a computer. Used by the Server and other services. Requires the Messenger service.


A signal sent to a customer, PBX or switching system to indicate an incoming call. A common form is the signal that rings a bell in the telephone set. Others signals can trigger such devices as whistles, gongs and chimes.

Alerting Call

A call for which the subject connection is in the Alerting state. This usually implies that the telephone instrument is ringing.

Alerting Pattern

An intelligent network term. Alerting pattern is a specific pattern used to alert a subscriber (e.g. distinctive ringing, tones etc.). See Q.931.

Alerting Signal

A ringing signal put on subscriber access lines to indicate an incoming call. Telcordia defines alerting signals more broadly; thus: "Alerting signals (for example, ringing, receiver off-hook) are transmitted over the loop to notify the customer of some activity on the line."

Alerting State

A state in which a device is alerting (e.g., ringing) or is being presented ( offered ) to a device. This indicates an attempt to connect a call to a device. The device may be a device such as a telephone station. The device may also be a routing or distribution type of device. This includes a ACD or Hunt Group device.


Software which provides Internet users with a transparent read capability of remote files at anonymous FTP sites.

Alexander Graham Bell

See Bell, Alexander Graham.


A prescribed finite set of well defined rules or processes for the solution of a problem in a finite number of steps. Explained in normal English, it is the mathematical formula for an operation, such as computing the check digits on packets of data that travel via packet switched networks. Algorithm derives from the name of the ninth-century Persian mathematician al-Khomeini, who also had a lot to do with the invention of algebra. The word algebra comes from the Arabic al-jabr, which first appeared in a treatise by al-Khwarizmi.

Algorithmic Language

An artificial language established for expressing a given class of algorithms.


Automatic Location Identification or Information. Working with Automatic Number Identification, the use of a database to associate a physical location with a telephone number. ALI is a feature of E-911 (Enhanced 911) systems. ALI is provided to agents answering E-911 calls. It may include information such as name, phone number, address, nearest cross street and special pre-existing conditions (i.e. hazardous materials). On some systems it may also provide the appropriate emergency service address for the particular address. ALI is retrieved from a computer database. The database may be held on site or at a remote location and may be maintained by the local phone company (or its parent) or another agency.


  1. You're called John Smith. But on computer systems, you call yourself Jack Plumppuding. The "Jack Plumpudding" is your alias.

  2. A feature of the Apple Macintosh System allowing the user to create a file that points to the original file. When you click on an alias, the original application is launched. Aliases can work across a network; so you can access a program residing on a file server or a Mac that runs file sharing.

  3. Unwanted signals generated during the A-to-D (Analog to Digital) conversion process. This is typically caused by a sampling rate that is too low to faithfully represent the original analog signal in digital form. Typically, a rate that is less than half the highest frequency to be sampled.

  4. A nickname for a domain or host computer on the Internet. See also Alias Email Address.

  5. An alias is an e-mail address that forwards its mail to a specified mailbox, masking the true name of the mailbox in which the mail is actually received. For example, could be an alias for

Alias Email Address

An Internet Service Provider (ISP) called (now taken over by AT&T) explains their definition of alias email address as follows : "To change your email address, you need to create an alias email ID. An alias email ID allows you to create a new email address for yourself that points back to your original email address. This service is great for people that registered with IBM Internet Connection Services, but did not get the email address they wanted when registering. The email alias ID can be between 3 and 32 characters in length. This allows you to choose an email alias ID much longer than your original user ID, which must be between 5 and 7 characters in length. For example, you may have been assigned the email address when registering. You could create an alias email ID that is more memorable, such as"


Distortion in a video signal. It shows up in different ways depending on the type of aliasing in question. When the sampling rate interferes with the frequency of program material the aliasing takes the form of artifact frequencies that are known as sidebands. Spectral aliasing is caused by interference between two frequencies such the luminance and chrominance signals. It appears as herringbone patterns, wavy lines where straight lines should be and lack of color fidelity. Temporal aliasing is caused when information is lost between line or field scans . It appears when a video camera is focused on a CRT and the lack of scanning synchronization produces a very annoying flickering on the screen of the receiving device.

Aliasing Noise

A distortion component that is created when frequencies present in a sampled signal are greater that one-half the sample rate. See Anti-aliasing Filter.

Aligned Bundle

A bundle of optical fibers in which the relative spatial coordinates of each fiber are the same at the two ends of the bundle. Also called "Coherent Bundle."


  1. The adjustment of components in a system for optimum performance.

  2. The process of adjusting a satellite dish to receive the strongest signal.

Alignment Error

In IEEE 802.3 networks, an error that occurs when the total number of bits of a received frame is not divisible by eight, i.e. not properly framed. Alignment errors are usually caused by frame damage due to collisions.


Access Lines In Service. See Access Line.


Automatic Line Insulation Testing. Equipment located in a Central Office which sequentially tests lines in the office for battery crosses and grounds.


An Administrative Law Judge appointed by a State Commission to review a Commission docket, such as a rate case or incentive regulation proposal, and to make recommendations to the Commissioners.

All Call Paging

With this feature, a user can broadcast an announcement ” a page ” to someone through the speakers of all the telephones on the system and, possibly, any external loudspeakers. If you want instant fame, ask your secretary to call all the airports in the country and page you. Mike Todd, the movie mogul, used to have this secretary perform this wonderful task. Mr. Todd gave gigantic egos a whole new meaning.

All Channel Tuning

Ability of a television set to receive all assigned channels: VHF and UHF, channels 2 through 83.

All Dielectric Cable

Cable made entirely of dielectric ( insulating ) materials without any metal conductors.

All Inputs Hostile

Measurement technique for troubleshooting networks, particularly for crosstalk, using worst case conditions (typically, full chroma signal on all inputs other than the one under test).

All Number Calling

Once upon a time, the first two digits of telephone exchanges sort of corresponded to their location. For example, MU-8 meant Murray Hill 8 in Murray Hill, Manhattan, New York City. Then the phone company started running out of letters , so it went to All Number Calling. The All Number Calling provides a theoretical maximum of 792 central office exchange (NNX) codes per area code (NPA). This is derived on the basis of 800 NXX code combinations (8x10x10) leaving out eight special service combinations, including 411, 611, 911.

All Ones Keep Alive

Alarm Indicating Signal (AIS). Also known as a "Blue Alarm Signal" or "All Ones Keep Alive," an AIS is an unframed all-ones bit pattern sent by equipment at the far end to indicate that an alarm condition exists upstream in a circuit leading to the downstream equipment. Keep-alive signals are required by the network facilities to prevent oscillation of the line repeaters which causes interference (i.e. cross-talk and bleeding) within adjacent channels. SONET defines four categories of AIS: Line AIS, STS Path AIS, VT Path AIS, DSn AIS.

All or Nothing Rule

The FCC rule that requires a carrier to choose a single regulatory framework ” price cap or rate of return ” for all operations at the federal level. Carriers are free to be rate of return in one state and price cap (or alternative regulation) in another.

All Trunks Busy

When a user tries to make an outside call through a telephone system and receives a "fast" busy signal (twice as many signals as a normal busy in the same amount of time), he is usually experiencing the joy of All Trunks Busy. No trunks are available to handle that call. The trunks are all being used at that time for other calls or are out of service. These days, many long distance companies are replacing a "fast" busy signal with a recording that might say something like, "I'm sorry. All circuits are busy. Please try your call later."

All-Silica Fiber

An optical fiber composed of a silica-based core and cladding. The presence of a protective polymer overcoat does not disqualify a fiber as an all-silica fiber, nor does the presence of a tight buffer.

Allan Variance

One half of the time average over the sum of the squares of The differences between successive readings of the frequency deviation sampled over the sampling period. The samples are taken with no dead-time between them. See Two-Sample Variance.

Allen, Robert

Chairman and CEO of AT&T from April, 1988 to November 1997 when C. Michael Armstrong took over. Allen became chairman and CEO of AT&T in April 1988 following the unexpected death of then-Chairman James E. Olson. Under Allen's leadership, the company evolved from a highly regulated utility to a successful competitor in the dynamic, fiercely competitive communications industry. In 1995, Allen made the bold decision to restructure AT&T into three companies, spinning off the company's equipment arm to become the very successful Lucent Technologies and its computer arm into specialty computer maker NCR.

Allen began his AT&T career at Indiana Bell in 1957 and rose steadily to hold officer posts there, at Bell of Pennsylvania, Illinois Bell, the Chesapeake and Potomac Telephone Companies and AT&T. He was the company's president and COO prior to being named CEO.

In 1980, Bob Allen headed a task force to look into AT&T's future. The recommendation of the task force: keep equipment manufacturing at all costs. When he became chairman, he sold AT&T's manufacturing arm off. It's now called Lucent Technologies.


To assign space or resources for a specific task. This is often used to refer to memory or disk space.

Allocated Channel

A Radio Frequency (RF) channel that is configured to allow use by Cellular Digital Packet Data (CDPD) transmissions.


  1. A method by which end users not presubscribed are assigned to long distance phone companies in the same ratio as customers who selected a long distance company before an end office conversion to equal access.

  2. The amount of stock in an initial public offering (IPO) granted by the underwriter to an investor. IPO allocations are determined based on a customer's commission volume, trading history, and type of investor. IPO allocations are normally communicated to investors the morning after the pricing. In the old days all technology IPOs went up on their first day of trading and, hence, if you got an allocation, you immediately made money. It was money for jam. These days, no more.

  3. In radio systems, the band of radio frequencies designated by upper and lower frequency limits and specified by the ITU/WARC for use by one or more of 38 terrestrial and space radio communications services under specified conditions.

Allocation Of Resources

A reason which CEOs give for not doing what they should be doing to grow their company.

Allowed Cell Rate

ACR. An ATM term. An ABR service parameter, ACR is the current rate in cells /sec at which a source is allowed to send. ACR is a parameter defined by the ATM Forum for ATM traffic management. ACR varies between the MCR and the PCR, and is dynamically controlled using congestion control mechanisms.


A combination of two or more metals that forms a new or different metal with specific or desirable qualities.


  1. AppWare Loadable Module. A visual computer telephony applications generator that works on Novell's NetWare. An ALM works by tying into Novell NetWare's NLMs. See Appware.

  2. Automated Loan Machine. Like an ATM (Automated Teller Machine), an ALM sits in the wall of a building or inside a building on a wall. However, instead of giving money you own, an ALM dispenses money in the form of an instant loan. One of the leading ALM manufacturing companies is Affinity Technologies of Columbia, South Carolina. Alan Fishman of Columbia Financial Partners contributed this definition. Mr. Fishman is a leading New York City venture capitalist, who helped Affinity get started. Mr. Fishman's company is Columbia Financial Partners.

  3. Airline Miles. The method used to calculate the distance (for pricing purposes) of the point-to-point long distance lines in long distance telephone networks. See Airline Mileage.

ALO Transaction

An ATP transaction (AppleTalk Transaction Protocol) in which the request is repeated until a response is received by the requester or until a maximum retry count is reached. This recovery mechanism ensures that the transaction request is executed at least once. See also ATP.


A method of data transmission in which the device transmits whenever it wants to. If it gets an acknowledgement from the device it's trying to reach, it continues to transmit. If not (as in the case of a collision with someone else trying to transmit simultaneously ), it starts all over again. The ALOHA method get its name from a dying satellite that was donated to university researchers in the Pacific. It was used to transmit data by satellites among South Sea islands, especially Hawaii. The ALOHA "method" ” called "transmit at will" ” was invented because the users were short of funds to develop more sophisticated data transmission protocols, and they had a free satellite, which typically had more bandwidth than they had stuff to send. See Alohanet.

Aloha Suite

Temporary office space, including phone, fax, email and Internet, provided to laid-off employees to help them create the appearance that they are still working while they search for a new job.


An experimental form of frequency modulation radio network developed by the University of Hawaii. Alohanet is implemented by creating transmission frames containing data, control information, and source and destination addresses which are broadcast for reception by the destination receiver and ignored by all others. Actually, Alohanet is an early version of Ethernet, the local area network technique. See Aloha.


Aluminum-polyethylene primary covering used as the sheath for aerial cable.


  1. Only alphabetic characters.

  2. The first (A) version of hardware or software. It typically has so many bugs you only let your employees play with it. A beta is the next version. It's a pre-release version and selected customers (and the press, sometimes) become your guinea pigs. After beta, and when the bugs are removed, comes "general availability" or "general release. That's when the product is finally available for buying by the general public."

Alpha Channel

The upper 8 bits of the 32-bit data path in some 24-bit graphics adapters. The alpha channel is used by some software for controlling the color information in the lower 24 bits.

Alpha Geek

The most knowledgeable, technically proficient person in an office or work group. "Ask Harry, he's the alpha geek around here."

Alpha Test

The first testing phase of a software version. Alpha tests are conducted in-house, before being promoted to beta test, which typically involves a real customer.


The ITU (International Telecommunications Union) phonetic alphabet is: Alpha, Bravo, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, Juliet, Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, X-Ray, Yankee and Zulu.


Only alphabetic characters. See also Alphanumeric .


A set of characters that contains both letters and numbers ” either individually or in combination. Numeric is 12345. Alphabetic is ABCDEF. Alphanumeric is 1A4F6HH8. American and Australian zip codes are numeric. Canadian and English postal codes are alphanumeric. No one knows why.

Alphanumeric Display

A display on a phone or console showing calling phone number, called number, trunk number, type of call, class of service and perhaps, some other characteristics of the call. It may also contain instructions as to how to move the call around, set up a conference call, etc. The display may be liquid crystal or light emitting diode. Typically, it's liquid crystal.

Alphanumeric Memory

A cellular radio feature that allows you to store names with auto-dial phone numbers.

ALPS circuit

A communication path across a TCP connection between a host reservation system and an ASCU. When MATIP encapsulation is used on an ALPS circuit, it is equivalent to a MATIP session.


  1. Active Line State, one possible state of an FDDI optical fiber.

  2. Additional listing.


Alternate Local Transport. Another term used for a provider of service other than the LEC. Interchangeable term with CLEC and CLSP.

Alt Newsgroups

A set of Usenet newsgroups containing articles on controversial subjects often considered outside the mainstream. Alt is an abbreviation for alternative. These newsgroups were originally created to avoid the rigorous process required to create an ordinary newsgroup. Some alt newsgroups contain valuable discussions on subjects ranging from agriculture to wolves , others contains sexually explicit material, and others are just for fun. Not all ISPs and online services give access to the complete set of alt newsgroups.

Altair Ethernet

Motorola's name for its wireless local area network, which transmits at the very high frequency of 18 to 18 megahertz . Altair users need to fill out a small, one-page FCC application in order to use the system.

Altazimuth Mount

A mounting, e.g., for a directional antenna, in which slewing takes place in the plane tangent to the surface of the Earth or other frame of reference and elevation about (above or below) that plane. Also called an X-Y Mount.


Association of Long distance TELephone companies. A trade association composed of alternative (to AT&T) long distance carriers and resellers of long distance services.

Alternate Access

Has the same meaning as Local Access except that the provider of the service is an entity other than the Exchange Carrier authorized or permitted to provide such service. The charges for Alternate Access may be specified in a private agreement rather than in a published or special tariff if private agreements are permitted by applicable governmental rules.

Alternate Access Provider

A carrier providing local access and transport other than the primary local exchange carrier.

Alternate Answering Position

Usually refers to a second receptionist's desk which has a telephone switchboard or console functioning like the main one. Also refers to when the main receptionist is away from his/her desk, or is very busy taking calls, the telephone system automatically sends the calls to another console or to a phone that will be answered .

Alternate Buffer

In a data communications device, the section of memory set aside for the transmission or receipt of data after the primary buffer is full. This helps the device control the flow of data so transmission is not interrupted due to lack of space for the incoming or outgoing data.

Alternate Entrance

A supplementary entrance facility into a building using a different routing to provide diversity of service and for assurance of service continuity.

Alternate Lock Code

A three-digit lock code to be used with the partial lock feature in some cellular phones.

Alternate Mark Inversion

See AMI.

Alternate Media Connector

A buildings network term. An optional module that plugs into a 1016, 2016, 3024 or 3124 repeater to provide an AUI, BNC, or fiber Media Expansion Port (MEP).

Alternate Recipient

An electronic messaging term. In X.400 terms, a user or distribution list that a recipient MTA (Message Transfer Agent) delivers a message to (if allowed) when the message cannot be sent to the preferred recipient.

Alternate Route

A second or subsequent choice path between two exchanges, usually consisting of two or more circuit groups in tandem. Sometimes called "alternative route" or "second-choice route."

Alternate Routing

  1. AR. Redirecting a call over alternate facilities when the first choice route for that call is unavailable. AR is a mechanism that supports the use of a new path after an attempt to set up a connection along a previously selected path fails. It's a feature used in network design and also in PBXs. For example, with PBXs it's a feature used with long distance calls that permits the telephone system (typically a PBX) to send calls over different (alternate) phone lines. It might do this because of congestion of the primary phone lines the calls would normally be sent over. Alternate routing is often confused with Least Cost Routing in which the telephone system chooses the least expensive way (available at that time) to route that call. Least Cost Routing typically works with so- called "look-up" tables in the memory of the PBX. These tables are put into the PBX by the user. The PBX does not automatically know how to route each call. It must be told by the user. That "telling" might be as simple as saying "all 312 area codes will go via the AT&T FX line." Or it might be as complex as actually listing which exchanges in the 312 area code go by which method. Least Cost Routing tells the calls to go over the lines which are perceived by the user to be the least costly way of getting the call from point A to point B. Alternate routing happens when the least cost routes get congested and alternate routes (typically more expensive) are found from the look-up tables in the PBX's memory.

  2. In the US emergency services telephone network, alternate routing is the ability to route 9-1-1 calls to an alternate location if the primary public safety answering point is busy or otherwise unavailable.

Alternate Service Provider

ASP. A fancy name for a new phone company which is not a traditional telephone company. Such could be a local, metropolitan or long distance phone company specializing in voice, data and video. Such a company, if it concentrated on local service, could also be known as CLEC, which stands for a Competitive Local Exchange Carrier. See CLEC.

Alternate Serving Wire Center

ASWC. When a building or customer is served by two different Central Offices, the one that is not his main central office is called the ASWC.

Alternate Serving Wire Center (ASWC) One of a Carrier's primary requirements is to make certain communications will not be interrupted totally by a facility failure. Verizon answers this need with Alternate Serving Wire Center (ASWC), an optional feature available for interstate DS1 and DS3 high capacity switched and special access services.

ASWC provides both wire center diversity and loop protection by enabling you and your customers to separate multiple DS1 and DS3 circuits over two geographically diverse paths. One path leads to the serving wire center; the other path goes to an alternate serving wire center. Two separate paths can also be provided for interoffice facilities (Interoffice Circuit Diversity). If there is a fault in the loop, a wire center, or an interoffice facility on one path, the other path continues unaffected at the capacity you have pre-established.


  • Available for switched and special access interstate DS1 and DS3 services

  • Provides an alternate path to an alternate serving wire center and loop protection

  • May be combined with the option of adding Interoffice Circuit Diversity to provide added security against facility disruptions between wire centers

  • Allows you to determine what percentage of traffic (optimal is 50%) will be routed over each path

  • Loop path provisioned via a self-healing SONET ring in some cases

  • ASWC and Interoffice Circuit Diversity available with tariff rates, where filed, where facilities permit (Otherwise, special construction charges may apply.)


  • Total service will not be interrupted in the event of a facility failure.

  • ASWC lets you obtain your service assurance from one point of contact, Verizon.

  • This may reduce or eliminate mileage charges.

How It Works:

Alternate Serving Wire Center provides 50% survivability to customers that divide their high capacity service equally between the two different wire centers. ASWC provides both wire center diversity and loop protection by enabling separate DS1 or DS3 circuits over two geographically diverse paths. One path leads to the serving wire center and the other leads to an alternate serving wire center. Should a fault occur in the loop, a wire center, or an interoffice facility on one path, the other path continues unaffected at the capacity you pre- established. Not all products, rates, and terms are available in all areas. Please see the tariff or contact your Account Manager for availability in your specific area.

Alternate Use

The ability to switch communications facilities from one type of service to another, i.e., voice to data, etc.

Alternate Voice Data

AVD. An older service which is a single transmission facility which can be used for either voice or data (up to 9600 bps). Arrangement includes a manually operated switch (on each end) to allow customers to alternately connect the line to their modem or PBX.

Alternating Current

See AC.

Alternative Access Provider

AAV. Another name for a CAP. See CAP.

Alternative Channel

A call center/marketing term. A competitive marketing strategy to expand the means by which a company can reach its customers. Direct marketing and specifically telephone-based marketing are major examples that have emerged in the highly competitive era of the '80s and '90s.

Alternative Non-Traffic Sensitive Cost-Recovery Plans

New charges proposed by the regional Bell holding companies to supplement subscriber line charges. In short, another charge on the subscriber with an interesting, though dubious, justification. They have not been fully implemented.

Alternative Regulation

Quasi-price cap regulatory plans at the state level that allow operators to set and raise prices and do not cap a carrier's profitability. Most independent and rural LECs participate in some state alternative regulatory plans.

Alternative Regulatory Framework



A machine which generates electricity which is alternating current. See AC.


Alternative Access Providers to the local telephone network i.e., Teleport.


Arithmetic Logic Unit. The part of the CPU (Central Processing Unit) that performs the arithmetic and logical operations. See Microprocessor.


Aluminum Oxide, Al2O3. Alumina ceramic is used as the substrate material on which is deposited thin conductive and resistive layers for thin film microwave integrated circuits.


The first known item made from aluminum was a rattle made for Napoleon III's infant son in the 1850s. Napoleon also provided his most honored guests with knives and forks made of pure aluminum. At the time, the newly discovered metal was so rare and difficult to process, it was considered more valuable than gold. Outside America, aluminum is spelled aluminium.


Aluminum-polyethylene, the sheath used for riser cable where a flame retardant sheath is required.

Always On

Always On is a feature of certain connections to the Internet ” Current analog dial-up services require the user to "make a call" to the ISP. The connection is only active during the duration of the call. Most xDSL implementations (including ADSL, UADSL, and SDSL) enable the connection to be always on in a fashion similar to a LAN.

Always On/Dynamic ISDN

See AO/DI.


See Amplitude Modulation. Also Access Module.

AM Detector

An electrical circuit which frequently uses diodes and filtering circuits to remove amplitude modulation from another radio frequency carrier or wave form.

AM Noise

The random and/or systematic variations in output power amplitude. Usually expressed in terms of dBc in a specified video bandwidth at a specified frequency removed from the carrier.

AM-PM Conversion

AM-PM conversion represents a shift in the phase delay of a signal when a transistor changes from small-signal to large-signal operating conditions. This parameter is specified for communications amplifiers , since AM-PM conversion results in distortion of a signal waveform.


Amplitude-Modulated Vestigial Sideband.


Automatic Message Accounting. A fancy name for the billing of phone calls. The telephone companies call AMA the distributed network function that measures usage of the network by subscribers and produces formatted records containing this usage information. Users of this formatted information include billing systems and other Operational Support (OS) systems. Corporate telephone customers know AMA as another name for Call Detail Recording or Station Message Detail Recording (SMDR). AMA equipment records call details. In a corporation, AMA records are used to generate billing for departments, to verify phone bills from carriers, to check for unauthorized calls. See AMA Tape and Call Accounting System (for a bigger explanation).

AMA Tape

A telephone company machine-readable magnetic tape which contains the customer's long distance calling and billing data for a given month.

AMA Teleprocessing System

AMATPS. The primary method for delivery of AMA data from the network to billing systems. The current AMATPS architecture consists of an AMA Transmitter (AMAT) and a collector.


AMA Data Networking System. In OSS, the next generation Bellcore system for the collection and transport of AMA data from central office switches to a billing system. See also AMA.

Amateur Radio Operator

Also known as HAM Radio Operator. A class of noncommercial private radio operator who use interactive radio as a hobby. There are six classes of licenses that are earned by examination, which the FCC sponsors.


AMA Teleprocessing System. In OSS, the Bellcore (now Telcordia) legacy system for collecting and transporting AMA data from central office switches to a billing system. The AMATPS consists of an AMA Transmitter and a collector. See also AMA.


When Apple cult leader Steve Jobs introduced the new iBook portable in May of 2001, he did not use the word "stunning" to describe it in the media briefing. He repeatedly called it "amazing." This word "amazing" seems to be the adjective most used in the Spring of 2001 at Apple. The new OS X was described as both amazing and stunning. See Cool.

Ambient Lighting

The general level of illumination throughout a room or area.

Ambient Noise

The level of noise present all the time. There is always noise, unless you're in an anechoic chamber . When measured with a sound level meter, it is usually measured in decibels above a reference pressure level of 0.00002 pascal in SI units, or 0.00002 dyne per square centimeter in cgs units.

Ambient Noise Level

See Ambient Noise.


Able to use a mouse with either hand.

Ambulance Chasing

See Spambulance Chasing.


Adds, Moves and Changes. Telephone-speak for adding phone extensions and trunks, moving phone extensions and changing them. In short, the AMCs covers the sort of work your telephone installer does in his monthly visit to your office. In some rapidly -changing firms, AMCs affect every phone every year. They refer to that as 100% AMC. AMCs can easily cost more than the initial cost of the phone system. Increasingly, AMCs can be done by a secretary from her PC over the LAN and connected to the phone system. The more you can do of this, the better. It will save time, money and the aggravation of new employees having to wait weeks before their new company's phone system finally recognizes that they exist.


Air Moving Device. IBM-speak for a fan with a feedback sensor to let the system know if the fan has failed.

Amdahl's Law

Dr. Gene Amdahl's observation in 1965 that computer system speed is governed by the speed of the slowest component. In most systems, the slowest component is the human operator, even if it's Amdahl himself.

America Online

The largest North American on-line computer and Internet access service. AOL provides e-mail, instant messaging, forums, software downloads, news, weather, sports, financial information, conferences, on-line gaming, an encyclopedia, and other features, to its subscribers.

American Bell, Inc.

  1. The predecessor to AT&T, American Bell was formed in 1880 as a Massachusetts corporation to supersede National Bell Telephone Company, which had consolidated the interests of the original Bell Telephone and New England Telephone Company. In the face of unfriendly Massachusetts corporate law, American Bell on December 30, 1899 was folded into American Telephone and Telegraph Corporation (AT&T), its wholly owned long distance subsidiary incorporated in New York state.

  2. The old name for the unregulated telephone equipment supply subsidiary of American Telephone & Telegraph. American Bell (deja vu all over again) was formed on January 1, 1983 by FCC mandate to market, sell and maintain newly manufactured equipment and enhanced services. American Bell Inc. had its name changed to AT&T Information Systems, becoming a division of AT&T. It has been reorganized many times. When it was American Bell, it was only selling telecommunications products and services to end users. When it become AT&T Information Systems, it sold AT&T phone systems and AT&T computer systems. It then merged with AT&T Long Lines, which was then called AT&T Communications and later called simply AT&T. Subsequently, it became known as AT&T Technologies, including the old Western Electric. In 1996, AT&T decided to split into three separate companies, with AT&T Technologies and Bell Telephone Laboratories becoming Lucent Technologies. Sadly, old gadgetry, knick-knacks and mementos bearing the name American Bell, Inc. have no marketable value as antiques or examples of American folk art. See also Lucent Technologies.

American Depository Receipt

ADR. A certificate issued by a U.S. bank for a share or shares of a non-U.S. company. Non-U.S. companies that wish to list on a U.S. exchange must abide by the regulatory and reporting standards of the Securities and Exchange Commission (SEC). These securities are called receipts because they represent a certain amount of the company's actual shares. Examples of ADRs are France Telecom, British Sky Broadcasting, and Equant.

American Mobile Telecommunications


American National Standards Institute


American National Standards Institute Character Set

The set of characters available. The character set includes, letters, numbers, symbols and foreign language characters.

American Registry for Internet Numbers


American Standard Code For Information Interchange

ASCII. The standard 7-bit code for transferring information asynchronously on local and long distance telecommunications lines. The ASCII code enables you to represent 128 separate numbers, letters, and control characters. By using an eighth bit ” as in extended ASCII or IBM's EBCDIC ” you can represent 256 different characters. ASCII often uses an eighth bit as a parity check or a way of encoding word processing symbols, not as a way of broadening the number of characters and symbols which it can represent. See also ASCII.

American Wire Gauge

AWG. Standard measuring gauge for non-ferrous conductors (i.e. non-iron and non- steel ). AWG covers copper , aluminum, and other conductors. Gauge is a measure of the diameter of the conductor. See AWG for a bigger explanation.


Ameritech Corp was one of the Regional Bell operating companies formed as a result of the AT&T Divestiture. Ameritech covered five states and included the operating telephone companies of Illinois Bell, Indiana Bell, Michigan Bell, Ohio Bell, and Wisconsin Bell. On October 9, 1999, Ameritech merged with (read acquired by) SBC, which used to be known as Southwestern Bell.


Alternate Mark Inversion. An older, but still common, line coding technique used in T-1 transmission systems. AMI generates alternately inverted positive and negative pulses to represent marks. In other words, pulses of alternating polarity are use to represent binary ones, with each such pulse being of the same amplitude, or signal strength. Binary zeros are represented with the generation of a null pulse, i.e., zero voltage. This technique prevents the buildup of DC voltage. As repeaters on T-1 circuits require regular pulse transitions (i.e., positive and negative voltages) to recover and regenerate timing on the circuit, long strings of zeros must be avoided. As a general rule, no more that 15 consecutive zeros can be transmitted without violating the ones density rule. B8ZS (Binary 8 with Zero Substitution), the newer line coding technique used in T-1 circuits, substitutes alternating bipolar pulses for the eighth zero in a string of eight consecutive zeros. B8ZS also supports clear channel communications of 64 Kbps per channel. See also B8ZS.

AMI Violation

A "mark" that has the same polarity as the previous "mark" in the transmission of alternate mark inversion (AMI) signals. Note: In some transmission protocols, AMI violations are deliberately introduced to facilitate synchronization or to signal a special event. See AMI.


See Audio Messaging Interchange Specification. A standard for networking voice mail systems.


  1. Analog Microwave Link.

  2. Actual Measured Loss.

Amortization Table

Let's say you borrow $100,000 to finance your house. You'd like to know how much you have to pay each month until your loan is finally paid off. An amortization table shows you that. A good one shows you four columns . The month you have to pay. The total amount you have to pay that month. The amount of what you paid that's interest. And the amount of what you paid that's principal.


See Ampere.

Amp hour

AH. A rating system telling you how long a battery will last. A battery with an amp-hour rating of 100 will supply 100 amps for one hour, 50 amps for two hours or 25 amps for four hours. It will run the four amp laptop I'm writing this on for at least 25 hours. That would be wonderful. However, the battery would weigh much more than my laptop. I probably could barely lift it. That would not be so wonderful. As usual, life is a bunch of tradeoffs.


The maximum current an insulated wire or cable can safely carry without exceeding either the insulation or jacket materials limitations. If the ampacity is exceeded, the conductor heats up due to the resistance to current flow as electromagnetic energy is converted to thermal energy. The insulation heats up, as well, perhaps to the point that it catches fire, which is not a good thing.

Amperage Rating

The amperage which may be safely applied to a circuit, service or equipment. See also Ampere.


Amp. The unit of measurement of electric current or the flow of electrons. One volt of potential across a one ohm impedance causes a current flow of one ampere. Amp is the abbreviation for ampere. It is mathematically equal to watts divided by volts . Note that in the electrical context, WATTS is spelled with two "Ts." In telecommunications, WATS, meaning Wide Area Telecommunications Service, is spelled with only one "T."

Ampere-hour Unit

Measurement of battery capacity, determined by multiplying the current delivered by the time it is delivered for. See Ampere.

Amphenol Connector

Amphenol is a manufacturer of electrical and electronic connectors. They make many different models, many of which are compatible with products made by other companies. Their most famous connector is the 25-pair connector used on 1A2 key telephones and for connecting cables to many electronic key systems and PBXs. The telephone companies call the 25-pair Amphenol connector used as a demarcation point the RJ-21X. The RJ-21X connector is made by other companies including 3M, AMP and TRW. People in the phone business often call non-Amphenol-made 25-pair connectors, amphenol connectors.

Amplified Handset

An amplified handset is the best phone gadget you can buy. You use it to crank up the volume of incoming calls (and in some cases the volume of outgoing calls) and save yourself enormous amounts of money on callbacks. "We have a bad line. I'll call you back." There are three types of amplified handsets:

  1. The handset with a built-in amplifier . These devices suck their power from the phone line and since the phone line doesn't have much power, you won't have much amplification. I'm not overly impressed with amplified handsets.

  2. The handset with amplifying circuits built into the phone. Ditto for our comments about power.

  3. The handset with the little external box amplifier which is powered by either AC or by several batteries, typically AA alkalines. Such an external amplifier will produce much greater amplification. This is the type I prefer.

Amplified Spontaneous Emission

A background noise mechanism common to all types of erbium-doped fiber amplifiers (EDFAs). It contributes to the noise figure of the EDFA which causes loss of signal-to-noise ratio (SNR). See Erbium-Doped Fiber Amplifier.


When telephone conversations travel through a medium, such as a copper wire, they encounter resistance and thus become weaker and more difficult to hear. An amplifier is an electrical device which strengthens the signal. Unfortunately, amplifiers in analog circuits also strengthen noise and other extraneous garbage on the line. Cascading amplifiers, therefore, compound, or accumulate, noise. Digital systems make use of regenerative repeaters, which regenerate (i.e., reshape, or reconstruct) the signal before amplifying it and sending it on its way. As a result, noise is much less prevalent and less likely to be amplified in digital systems, whether one or many repeaters are in place. The ultimate yield of a repeater in a digital environment is that of improved error performance, which also yields improved throughput, assuming that error correction involves retransmission. See also Repeater and Throughput.


Signal strength, or signal power. Also referred to as the wave "height." See Amplitude Modulation for better understanding.

Amplitude Distortion

The difference between the output wave shape and the input wave shape.

Amplitude Equalizer

A corrective network that is designed to modify the amplitude characteristics of a circuit or system over a desired frequency range. Such devices may be fixed, manually adjustable, or automatic.

Amplitude Intensity Modulation

AIM. See Intensity Modulation.

Amplitude Modulation

Also called AM, it's a method of adding information to an electronic signal in which the signal is varied by its height to impose information on it.

click to expand

"Modulation" is the term given to imposing information on an electrical signal. The information being carried causes the amplitude (height of the sine wave) to vary. In the case of LANs, the change in the signal is registered by the receiving device as a 1 or a 0. A combination of these conveys different information, such as letters, numbers, punctuation marks, or control characters. In the world of modems, digital bit streams can be transmitted over an analog network by amplitude modulation, with the carrier frequency being modulated to reflect a 1 bit by a high amplitude sine wave (or series of sine waves) and a 0 bit with a low amplitude sine wave or (series of sine waves). The principal forms of Amplitude Modulation are

QDM: Double-band Amplitude Modulation

QAM: Quadrature Amplitude Modulation

SSB: Single-sideband Modulation

VSB: Vestigial Sideband Modulation

Contrast with Frequency Modulation and Phase Shift Keying.

Amplitude Modulation Equivalent

AME. See Compatible Sideband Transmission.

Amplitude-vs.-Frequency Distortion

Distortion in a transmission system caused by nonuniform attenuation, or gain, in the system with respect to frequency under specified operating conditions. See frequency distortion.


Advanced Mobile Phone Service. It's another word for the North American analog cellular phone system. The spectrum allocated to AMPS is shared by two cellular phone companies in each area or region (geographic market). This system was deployed during the 1980s in North America. Most other parts of the world deployed cellular later and went straight to digital. See AMP (the measure of electricity and GSM).


  1. Automated Meter Reading. The automated reading of utility meters, generally power utility meters . AMR can make of wired and wireless technology, including cellular and LEOs (Low Earth Orbiting satellites). AMR involves a huge capital investment, but saves a lot of labor ” i.e. the labor of having someone drive a truck to your house and physically read your meter.

  2. See Adaptive Multi-Rate Speech Codec.


Adjusted Main Ring Length.


  1. Account Management System.

  2. Attendant Management System. An NEC term. With the NEAX2400 IMS, the AMS is an on-screen, dynamic Open Applications Interface (OAI) computer application that emulates and enhances attendant console capabilities. A typical AMS workstation combines the NEC HDAC console and headset with a color display and standard keyboard. The computer is equipped with the UNIX System V operating system, the NEC Applications Manager support platform, and a comprehensive package of software components. Communication between the HDAC and the AMS computer software is made possible by the OAI connection between the computer and the NEAX2400 IMS (ICS).


Amsterdam Internet Exchange. See IX.


American Mobile Telecommunications Association. An organization created to represent the interests of the U.S. commercial trunked radio industry, which generally is known as SMR (Switched Mobile Radio). In 1994, the AMTA spawned a sister organization IWTA (International Wireless Telecommunications Association), which represents similar interests on a worldwide basis. See also SMR.


Automated Maritime Telecommunications System.


Access network.


  1. Assigned Night Answer.

  2. Automatic Network Analyzer. A computer controlled test system that measures microwave devices in terms of their small signal S-parameters. The use of this instrument by both engineering and production permits quick and accurate characterization of the input and output impedance, gain, reverse isolation of individual units and the degree of match between units.


Automatic Number Announcement Circuit. A telephone number that provides access into a telephone company system that announces the telephone number of the circuit that you are using. It works regardless of whether the number is published or non-published. The ANAC is intended for the use of telephone company technicians when they are installing or troubleshooting your service. Hackers, crackers, phreakers, toll fraud artists and others use the ANAC to find out your number so that they can gain illegal access into your system through a modem line, for example. I could tell you what your ANAC is, or tell you how to find out, but I won't. It's for your own good. Trust me on this one.


Comes from the word "analogous," which means "similar to." In telephone transmission, the signal being transmitted ” voice, video, or image ” is "analogous" to the original signal. In other words, if you were able to see the natural acoustical compression waves that transmit voice in its native form, and compare them to the representation of the corresponding electrical signals on an oscilloscope as the same voice information is transmitted on a phone line, the two signals would look essentially the same. The only basic difference is that the acoustical voice compression waves are converted into electrical signals, which also travel in smooth wave form. In consideration of such factors as crosstalk, the electrical signals are restricted along the parameters of amplitude (i.e., power level, which is used to represent volume) and frequency (which is used to represent pitch, or tone). In both acoustical and electrical forms, the voice signal is in the form of a smooth and continuous energy flow, which varies along the parameters of amplitude and frequency. In telecommunications, analog means telephone transmission and/or switching which is not digital, and which therefore is not represented in discrete terms such as voltage on/off or light pulse on/off. Outside the telecom industry, analog is often called linear and covers the physical world of time, temperature, pressure, sound, which are represented by time-variant electrical characteristics, such as frequency and voltage. See Analog Transmission and Sine Wave.

Analog Bridge

A circuit which allows a normal two-person voice conversation to be extended to include a third person without degrading the quality of the call.

Analog Carrier

The first carrier-loop system, which emerged during the 1970s and was used to provide improved voice-quality transmission to subscribers who were located at distances too remote to be served by the central office. In this system, multiplexing occurred at the central office, and there was little value added at the analog box deployed on the subscriber side. While analog carriers did provide an advantage over previous systems, they were difficult to install and often resulted in inconsistent quality of service.

Analog Cellular

The current standard for cellular communications.

Analog Channel

A channel which transmits in analog waveforms. See Analog.

Analog Channel Compression

A technique for squeezing more than one program into a single channel using analog processes.

Analog Chips

Analog chips translate real-world phenomena ” like motion, sound, temperature, pressure and light ” into electronic or mechanical digital patterns that can be understood by their digital counterparts as for example when a song is recorded for a CD. An analog processor performs the opposite, taking the digital signals, for example off the CD, and converting them into analog sounds which we can enjoy.

Analog Circuit

A circuit which is analog, rather than digital, in nature. As all transmission circuits make use of electromagnetic energy (i.e., electricity, radio, or light), they all start with analog. If the circuit, on the other hand, is to operate in digital mode, the analog carrier (i.e., the specific frequency that carries the signal), is varied in terms of discrete levels of voltage, amplitude, presence (i.e., on/off), or some other parameter. See also Analog.

Analog Computer

A computer that performs its tasks by measuring continuous physical variables ” pressure, voltage, flow ” and manipulating these variables to produce a solution, which is then converted into a numerical equivalent. Analog computers are largely used as special purpose machines in scientific or technical applications. The earliest analog computers were purely mechanical devices with levers, cogs, cams, etc., representing the data or operator values. Modern analog computers typically employ electrical parameters such as voltage, resistance, or current to represent the quantities being manipulated. See also Analog Processor.

Analog Decoder

A circuit that performs decoding using analog circuit techniques rather than digital circuit techniques. (For example, decoding a video signal.)

Analog Digital Converter

An A/D Converter (pronounced "A to D Converter"), or ADC. A device which converts an analog signal to a digital signal.

Analog Driver

An accessory circuit for an oscillator of filter which permits its frequency to be changed by a continuously varying signal.

Analog Facsimile

Facsimile which can transmit and receive grey shadings ” not just black and white. It is called analog because of its ability to transmit what appear to be continuous shades of grey. "Analog" facsimile is usually transmitted digitally.

Analog Fiber Video Network

Implies a network in which fiber optic cable links entities together, with the video transmitted in its original analog format. Many of these systems use an "everybody on" philosophy, in which each participating entity on the network has its own channel and the other entities simply purchase a modulator (like a television tuner, for about $250) for each of the other parties, or channels with which they wish to interact. The practical limit to such a system is 16 channels, though most analog fiber networks link up no more than four entities at a time so that the participants see four monitors (TV sets) . . . one for each of the "live" participating sites. The advantage of analog fiber over digital fiber is that an expensive CODEC at each site is not required. The disadvantage is the relatively large bandwidth requirements that result in higher costs of fiber.

Analog Front End

AFE. The analog front end is responsible for converting the digital signal to analog and force the signal onto the twisted pair line. it also the part of the fax machine that converts between the digitally modulated signal and the analog signal used on the telephone line.

Analog Inverter

A device which inverts a wave from, i.e. turns it upside down.

Analog Loop-back

A method of testing modems and data terminals by disconnecting the device from the telephone line and looping a signal out through the device's transmit side and in through its receive side. The test tells if the trouble is with the telephone line or with the modem.

Analog Microwave

A microwave system in which the digital bit stream is modulated by a modem and then frequency shifted up to the appropriate microwave carrier frequency. Contrast with Digital Microwave.

Analog Monitor

A computer screen that uses an analog signal, a smoothly varying value of current or voltage that varies continuously. VGA, SVGA and Macintosh models are examples of analog monitors. Most computer screens are analog. Most analog monitors are designed to accept input signals at a precise frequency. Higher frequencies are needed to carry higher-resolution images to the monitor. For this reason, multiscanning monitors have been developed that automatically adjust themselves to the incoming frequency. See also Analog and Digital Monitor.

Analog Multiplier

A circuit that produces an output that is linearly proportional to the product of the two analog inputs.

Analog Private-Line Service

A dedicated circuit that transmits information between two or more points. It uses analog transmission signals and is engineered for 300 to 3,000 Hz with a net maximum loss of 16 dB.

Analog Processor

The type of processor used in an analog computer. A processor serves as the brains of a computer, taking data inputs, performing mathematical processes on them, and providing results in the form of data outputs. An analog processor works on the basis of analog, rather than digital, inputs, performs its processes on an analog basis, and provides analog outputs. While analog processors and computers may seem obsolete, they are extremely valuable in certain design applications which involve continuously variable shapes and speeds which cannot effectively be represented in discrete digital terms. Examples include automobile and aircraft design. For example, the design of an automobile carburetor, internal combustion engine, and entire drive train must consider the fact that acceleration is a relatively smooth process, rather than one that takes place in a herky-jerky mode involving discrete steps. Similarly, an automobile braking system must deal with a smooth process of deceleration. As another example, much contemporary aircraft design work focuses on the fluid and dynamic changes in the shape of aircraft wings which can reshape themselves in the event of turbulence, temperature changes, or other changes in the environment in which they must operate. See also Analog Computer.

Analog Recording

System of recording in which music is converted into electrical impulses that form "patterns" in the grooves of phonograph record masters or in the oxide particles of master tapes representing (or analogous to) musical waveforms.

Analog Semiconductor

Analog semiconductors are essentially the "translators" between the wave-form world of man (light, heat, pressure, and sound all move in waves) and the digital world ("ones" and "zeros") of computers. Analog semiconductors act as amplifiers in strengthening a weak signal, as converters to turn a signal from wave-form to digital and back again, and as voltage regulators, stepping down a signal from higher to lower power, also called power management.

Analog Signal

A signal in the form of a continuous wave varying in step with the actual transmitted information; attempts to transmit an exact replica of the inputted signal down a communications channel. See Analog and all the various definitions starting with Analog.

Analog Switch

Telephone switching equipment that switches signals without changing the analog form of the original phone call. The major form of analog switching is circuit switching. Most switching is now done digitally.

Analog Synchronization

A synchronization control system in which the relationship between the actual phase error between clocks and the error signal device is a continuous function over a given range.

Analog Transmission

A way of sending signals ” voice, video, data ” in which the transmitted signal is analogous to the original signal. In other words, if you spoke into a microphone and saw your voice on an oscilloscope and you took the same voice as it was transmitted on the phone line and threw that signal onto the oscilloscope, the two signals would look essentially the same. The only difference would be that the electrically transmitted signal would be at a higher frequency. Most transmission is now done digitally.

Analog Video

Signals represented by an infinite number of smooth transitions between video levels. TV signals are analog. By contrast, a digital video signal assigns a finite set of levels. Because computer signals are digital, analog video must be converted into a digital form before it can be shown on a computer screen.

Analog Wireless

The dominant radio transmission standard in the United States; also called AMPS.


An English/European way of spelling analog, which is the correct North American spelling. See Analog.


Unequally scaled in vertical and horizontal dimensions.


All Number Calling. The dialing plan used in telephone networks. Consisting of all numbers, ANC replaced the old U.S. system which consisted of two letters and five numbers (2L + 5N). In other words, the GR (Greenwood) exchange became 47, PA (Pennsylvania) became 72, and UL (Ulysses) became 85. Remember the Glenn Miller hit, "Pennsylvania 6-5000?" Those old exchanges were charming, often reflecting the character of the communities to which they were assigned. However, and as the number of telephone numbers grew, we ran out of alpha prefixes that included the first two letters of meaningful words. Eventually, we had to use the 1 on the dial in the second position of the prefix; there are no letters associated with that number. Hence, All Number Calling.


Advanced Networked Cities And Regions Association. A formal association of cities and regions exploring advanced uses of information technology. ANCARA was founded in 1996 by the regions /cities of Eindhoven (The Netherlands), Kansai (Japan), Orlando (Florida), Silicon Valley (California), Singapore, and Stockholm (Sweden). The intent is to accelerate the development of the Global Information Infrastructure (GII). See also GII.

Ancestor Node

An ATM term. A logical group node that has a direct parent relationship to a given node (i.e., it is the parent of that node, or the parent's parent.)


A hyperlinked word or group of words. An anchor is the same as a hyperlink ” the underlined words or phrases you click on in World Wide Web documents to jump to another screen or page. The word anchor is used less often than hyperlink, but it maintains the seafaring theme of navigating and surfing the Net. See also Hyperlink.

Anchorage Accord

A milestone ATM Forum document (April 12, 1998) so named because of the meeting location, the Anchorage Accord outlines which versions of ATM Forum specifications vendors should implement. ATM Forum specifications comprise approximately 60 baseline specifications for successful market entry of ATM products and services. Included are Broadband InterCarrier Interface (BICI), Interim Local Management Interface (ILMI), LAN Emulation (LANE), network management, Private Network Node Interface (PNNI), signaling, SMDS (Switched Multimegabit Data Service) and IP (Internet Protocol) over ATM, traffic management, and a number of physical interfaces. The accord also limits the conditions under which specifications are revised in order to cut down on future confusion. See also ATM Forum.

Anchor System

A cellular term. An anchor system is the system that maintains the connection to the PSTN (Public Switched Telephone Network) during the process of call handoff from one cell site to another. In this context, a "system" comprises all of the cellular carrier's MSCs (Mobile Switching Centers) serving a particular geographic area, and all of the cell sites supported by the MSCs. See also MSC.

Ancillary Charges

Charges for supplementary services comprised of optional features, which may consist of both non-recurring and monthly charges.


Automatic Digital Network Dialing. A digital private line service that transmits voice, data, video and other digital signals.

AND Gate

A digital device which outputs a high state if either of its inputs are high.

AND Logic Gate

A type of logic gate which uses AND logic. The output of an AND logic gate would consider the first and second input.

And Statement

See Not Statement.

Anechoic Chamber

A perfectly quiet room. A room in which sound or radio waves do not reflect off the walls. An anechoic chamber is the only place in which a speakerphone will work perfectly . The more a room resembles an anechoic chamber ” i.e. lots of drapes, plush carpet, etc. ” the better a speakerphone will work.


A device which measures wind speed and direction.


Investor in an early stage technology start-up. Typically an angel invests when the company is little more than an idea, a simple business plan and several management people, but rarely a full management team.

Angle Bracket

The term for these two brackets < and >. These two brackets have major use in the HTML language. See HTML.

Angle Modulation

Modulation in which phase angle or frequency of a sine wave carrier is varied.

Angle of Arrival

AOA. A class of Position Determination Technology in which a mobile radio unit's position is calculated based on the direction of its transmitted signal measured from two or more receiving sites; also known as triangulation. Employed in certain wireless E9-1-1 solutions. See also Time Difference of Arrival.

Angle Of Deviation

In fiber optics, the net angular deflection experienced by a light ray after one or more refractions or reflections. The term is generally used in reference to prisms, assuming air interfaces. The angle of deviation is then the angle between the incident ray and the emergent ray.

Angle of Incidence

The angle between an incident ray and the normal to a reflecting or refracting surface.

Angled End

An optical fiber whose end is deliberately polished at an angle to reduce reflections.

Angry fruit salad

A terrible visual interface on a web site or a software screen that has far too many colors.


One ten-millionth of a millimeter. Angstroms are primarily used to express electromagnetic wavelengths, including and particularly optical wavelengths . It is also called an Angstrom unit. It is named after Anders Jonas Angstrom, a Swedish astronomer and physicist , who lived 1814-74. It is said that the 128-bit addressing scheme of IPv6 provides enough unique IP addresses to theoretically provide 1,500 per square angstrom of the earth's surface.

Angular circumference

The measurement of the amount of bend in a fiber- optic cable.

Angular Misalignment Loss

The optical power loss caused by angular deviation from the optimum alignment of source to optical fiber ” fiber-to-fiber, or fiber-to- detector.


Automatic Number Identification. ANI provides for the transmission through the network of the BN (Billing Number), versus the telephone number, of the originating party (i.e., the calling person, also called party in the phone business). ANI originally was intended exclusively for the use of the long distance and local phone carriers for billing purposes. ANI information is sent through the network, from the originating central office, through all intermediate tandem offices, to the terminating central office. The information originally was sent over analog trunks in the form of DTMF (Dual Tone MultiFrequency) signals, although contemporary networks usually pass the information through the digital SS7 (Signaling System 7) network. For some years , ANI has been available to end user organizations, as well. In order to gain access to ANI data, you must have a "trunk side" connection, which carries an additional charge. Much like CLID (Calling Line IDentification), ANI delivers the number of the calling party. Unlike CLID, ANI does not depend on the presence of SS7 throughout the entire network. Also unlike CLID, ANI information cannot be blocked by the calling party. So, let's pretend that you are running a large call center. A customer calls you. Before the call is even connected to your ACD (Automatic Call Distributor), ANI presents the BN of the calling party to the ACD. Your ACD captures the BN, dips into a computer database and matches that number with the profile of the caller. As your telephone agent answers the call, he gets a "screen pop" with information about the caller, and he answers the call with "Good morning, Mr. Newton. This is Ray. I read about ANI in your Dictionary. Isn't it wonderful!" Some large users say they save as much as 30 seconds on the average IN-WATS call by knowing the phone number of the person calling them and being able to use that information to access information about them in the company database. They avoid asking regular customers for routine identification information (like their address and phone number) since it is all there in the database. See also Caller ID, CLASS, Common Channel Signaling, DNIS, Flex ANI, ISDN and ISUP.

ANI Identification

Want to know what number you're calling from? Call your cell phone.


ANI II information digits are two digits that are sent with the originating telephone number to identify the type of originating station. Examples include "00" for a regular line; "06" for hotel/motel; "27" for coin phone; "61, "62," and "63" for cellular phones; and "70" for private pay stations . In a SS7 network, the ANI II code is in the form of an Originating Line Indicator, which is populated in the Originating Line Information Parameter (OLIP) within a SS7 Initial Address Message (IAM).

ANI II Codes

ANI II digits are two digits that are sent with the originating telephone number identifying the type of originating station (e.g., Hotel/Motel, etc.). The ANI II code is populated in the Originating Line Information Parameter (OLIP) within a SS7 Initial Address Message.


Someone who communicates with you telepathically.


The process of displaying a sequential series of still images to achieve a motion effect.


Anime (pronounced ah-knee-may) is an artistic and sensual type of Japanese animation that can be found on hundreds of Web sites.


Pertaining to transmission in which the time interval separating any two significant instants in sequential signals is not necessarily related to the time interval separating any other two significant instants. Isochronous and anisochronous are characteristics, while synchronous and asynchronous are relationships.


Pertaining to a material whose electrical or optical properties vary with the direction of propagation or with different polarizations of a traveling wave.

Anisotropic Filtering

A graphics term. A method of filtering textures using a nonsquare area. With this method, a pixel may encompass information from many texture elements (called texel) in one direction and fewer in another. It yields sharp textures on objects that slant away from the viewing plane, such as a road running into the distance.

Ankle Biter

A person who aspires to be a hacker/cracker but has very limited knowledge or skills related to computer systems. Usually associated with young teens who collect and use simple malicious programs obtained from the Internet.


ANswer Message. The fourth of the ISUP call set-up messages. A message sent in the backward direction indicating that the call has been answered. See ISUP and Common Channel Signaling.


Artificial Neural Network. See Neural Network.


The process of using heat and gradual cooling to soften a metal such as copper, making it less brittle and, therefore, less likely to break when it is flexed.

Annex A

The first of the frame relay standard extensions, Annex A outlines provisions for a Local Management Interface (LMI) between customer premises equipment and the frame relay network for the purpose of querying network status information.

Annex D

The second frame relay standard extension dealing with the communication and signaling between customer premises equipment and frame relay network equipment for the purpose of querying network status information.


A Web homepage which seems to have been abandoned for some time. Most of the links are out of date. It's been orphaned.


Marking such as that done by highlighting, underlining, text, or freehand drawing. See Annotations.


Notes that you can add to Web documents. These notes are stored on your local hard disk and are available each time that you access a document. This feature is found in NCSA Mosaic, but not Netscape Communicator or Microsoft's Internet Explorer.

Announcement Service

Allows a phone user to hear a recording when he dials a certain phone number or extension. These days, announcement services are provided increasingly by totally solid-state digital announcers. These gadgets are more reliable, deliver a clearer message and last much longer than analog tape-based machines (like answering machines), which use recording tape.

Announcement System

An arrangement for providing information by means of recorded announcements.

Annoyance Call Bureau

The department in your local phone company which you call when you need help with annoying or harassing phone calls you are receiving. The Bureau will recommend you file a report with your local phone company. And then it may apply Trap and Trace equipment and techniques to try to locate the source of your annoying phone calls. The Annoyance Call Bureau is the stepchild of the phone industry, which means it is typically underfunded. See Trap and Trace.


You are typing away with a new shareware program that suddenly stops itself and a portal pops up from the author asking for a promise to pay in order to continue.

Annual Percentage Rate

APR. A percentage calculation of the finance charge portion of a financing contact.

Annular Ring

An indicator (or ring) around the circumference of the coaxial cable every so many feet ” often 2.5 meters (8.2 feet) ” to indicate a point where transceivers are to be connected. Same as transceiver attachment mark.


Original name for the indicator on magnetic switchboards which indicates the particular line that is calling the exchange. Now it is simply a light, a bell or a device that tells you something. That something might be the ringing of a phone or it might be a problem that you're having with some piece of remote equipment. A communicating annunciator is a sophisticated device that is connected to a phone line and gets on that line (dial-up or leased) to let you know that something is broken.

Anomalous Propagation

AP. Abnormal propagation caused by fluctuations in the properties (such as density and refractive index) of the propagation medium. AP may result in the reception of signals well beyond the distances usually expected.


An impedance discontinuity causing an undesired signal reflection in a transmission cable.

Anonymous Call Rejection

ACR. A service some local phone companies are providing their subscribers. It allows subscribers to automatically stop certain calls from ringing their phone. The calls stopped are "restricted," namely they would be displayed as "P" or "Private" on a subscriber's Caller ID device, meaning that the calling person did not send you his calling number. The person who makes such a call would hear, "We're sorry. The party you have reached is not accepting private calls. To make your call, hang up, dial *82 or 1182 on a rotary phone and re-dial." The caller will be able to reach you only by re-dialing without restricting display of his or her number.

Anonymous FTP

Anonymous FTP allows a user to retrieve documents, files, programs, and other archived data from anywhere on the Internet without having to establish a userid and password. By using the special userid of anonymous, the network user bypasses local security checks and can access publicly accessible files on the remote system. See also FTP.

In short, anonymous FTP ia a way of logging in anonymously to distant hosts on the Internet and often freeware (free software) from the Internet. With an implementation of the FTP protocol, users can get public domain software from Internet sites, using the word "anonymous" for a login ID, and their userid@hostname.domain as the password. A database called Archie contains a list of what is available from anonymous FTP sites, and can be reached at "" and at "" See FTP.

Anonymous Telephone Number

A telephone number that should not be displayed or voiced back to the called party. Such a designation is stored in switch memory and is included in signaling information sent to the terminating switch for interSPCS calls.


ANalysis Of VAriance.


Answer. (What else?) (Which is a question, the ANS to which is provided below.)


Alternate Network Service Agreement. An ISDN term. Under ANSA, customers who reside in areas where the central office switch does not support ISDN can be serviced from a neighboring central office at no additional charge. From the customer's perspective, ISDN is readily available and affordable, but the customer MUST agree to migrate to the local central office if and when service becomes available. In most cases this will involve a change in phone number. This agreement pertains to BellSouth customers only.


American National Standards Institute. A standards-setting, non-government organization founded in 1918, which develops and publishes standards for transmission codes, protocols and high-level languages for "voluntary" use in the United States. In a press release, ANSI described itself as "a private non-profit membership organization that coordinates the U.S. voluntary standards system, bringing together interests from the private and public sectors to develop voluntary standards for a wide array of U.S. industries. ANSI is the official U.S. member body to the world's leading standards bodies ” the International Organization for Standardization (IOS or ISO) and the International Electronic Commission (IEC) via the U.S. National Committee. The Institute's membership includes approximately 1,300 national and international companies, 30 government agencies, 20 institutions and 250 professional, technical, trade, labor and consumer organizations." ANSI is located at 11 West 42 Street, 13th Floor, New York NY 10036 212-642-4900. ANSI puts out a biweekly newsletter called "ANSI Standards in Action. See also ANSI Character Set, CCITT, ECMA, IEEE, and ISO.

ANSI T1.110-1987

Signaling System 7 (SS7) - General Information.

ANSI T1.111-1988

Signaling System 7 (SS7) - Message Transfer Part (MTP).

ANSI T1.112-1988

Signaling System 7 (SS7) - Signaling Connection Control Part (SCCP).

ANSI T1.113-1988

Signaling System 7 (SS7) - Integrated Services Digital Network (ISDN) user part.

ANSI T1.114-1988

Signaling System 7 (SS7) - Transaction Capability Application Part (TCAP).

ANSI T1.206

Digital Exchanges and PBXs - Digital circuit loopback test lines.

ANSI T1.227-1995

Telecommunications Operations Administration Maintenance and Provisioning.

ANSI T1.301

ANSI ADPCM standard.

ANSI T1.401-1988

Interface between carriers and customer installations - Analog voice grade switched access lines using loop-start and ground-start signaling.

ANSI T1.501-1988

Network performance - Tandem encoding limits for 32 Kbit/s Adaptive Differential Pulse-Code Modulation (ADPCM).

ANSI T1.601-1988

Integrated Services Digital Network (ISDN) - Basic access interface for use on metallic loops for application on the network side of the NT (Layer 1 specification).

ANSI T1.605-1989

Integrated Services Digital Network (ISDN) - Basic access interface for S and T reference points (Layer 1 specification).


ANSI's standard for telecommunications network performance standards, switched exchange access network transmission performance standard exchange carrier-tointerexchange carrier standards.


ANSI's SONET standard.


A committee sponsored by the American National Standards Institute (ANSI) that is responsible for a variety of system interconnection standards. The committee has produced draft standards for high-speed coaxial cable bus and fiber optic ring local networks.


Twisted-Pair Distributed Data Interface (TPDDI) is a new technology that allows users to run the FDDI standard 100 Mbps transmission speed over twisted-pair wiring. Unshielded twisted-pair has been tested for distances over 50 meters (164 feet). TPDDI is designed to help users make an earlier transition to 100 Mbps at the workstation.

ANSI Character Set

The American National Standards Institute 8-bit character set. It contains 256 characters.

Answer Back

A signal or tone sent by a receiving equipment or data set to the sending station to indicate that it is ready to accept transmission. Or a signal or tone sent to acknowledge receipt of a transmission. See Answer Supervision.

Answer Back Supervision

Another word for answer supervision. See Answer Supervision.

Answer Call

The name of a Bell Atlantic service. Here are Bell Atlantic's words. Answer Call is an answering machine without the machine. This automated messaging service answers your calls right through your touch-tone phone ” 24 hours a day ” even when you're on the phone. And since it's on Bell Atlantic network, there's no equipment to buy...nothing to turn wires to connect... and no maintenance. By simply dialing a private passcode, you can listen to your messages, replay them or even change your greeting. What's more, Answer Call gives you the option of providing your employees (who share one line) with up to eight private "mailboxes" to receive and retrieve their own messages.

Answer Delay

  1. The time from the beginning of ringing until the called station answers.

  2. Any time delay between a "request-to-send" signal and the receipt of the first character of the response message. A three-digit number identifying one of the assigned geographic area codes in the North American direct distance dialing numbering plan.

Answer Detect

The use of a digital signal processing technique to determine the presence of voice energy on a telephone line. It is used with call (answer) supervision, to identify an answered line. It's beginning to be used with computerized dialing equipment as it eliminates the need for a telephone representative to constantly monitor call set-up progress on each telephone line in the event a call is answered. See Answer Supervision and Answer Signal.

Answer Message

ANM. A CCS/SS7 signaling message that informs the signaling points involved in a telephone call that the call has been answered and that call charging should start.

Answer Mode

When a modem is set by the user to receive data, it is in Answer Mode. In any conversation involving two computers, two terminals or one computer and one terminal, one side of the conversation must always be in Answer Mode. Putting a modem/computer in answer mode is sometimes done through software and sometimes through hardware, i.e. a switch on the side of the machine. You cannot run a data communications "conversation" if both sending and receiving equipment are in answer mode. Computers ” mainframe and mini ” which receive a lot of phone calls are typically put in answer mode." The terminals or computers calling them are typically in transmit mode.

Answer Receive Ratio

ASR. A measurement of the effectiveness of a telecommunications service offering. ASR is the relationship between the number of line seizures and the number of answered (i.e., completed) calls. Did you ever get dial tone, and then a "fast busy" because the destination device is unavailable? That is not good for ASR. Did you ever get dial tone, and then an answered call because the destination device is available? That is good for ASR.

Answer Signal

A supervisory signal, usually in the form of a closed loop, returned from the called telephone to the originating switch when the called party answers. This signal stops the ringback signal from being returned to the caller.

Answer Supervision

Follow this scenario: I call you long distance. My central office must know when you answer your phone so my central office can start billing me for the call. It works like this: when you, the called party, answer your phone, your central office sends a signal back to my central office (the originating CO). This tells my central office to start billing me for the call. This signal is called Answer Supervision. Before the divestiture of the Bell System in early 1984, most of the nation's long distance companies ” with the exception of AT&T Communications ” did not receive Answer Supervision. They did not know precisely when the called party answered. So they started their billing cycle after some time ” 20 or 30 seconds after the caller completed dialing. These long distance companies presumed that after this time, some one will have answered and the call will be in progress and can then be timed and billed. Without Answer Supervision, their billing of calls is inaccurate. They may bill for calls which didn't occur. And you may pay more for calls which did occur.

With the divestiture of the Bell System, and the introduction of Equal Access, the local phone companies have been told by the FCC that they must provide accurate answer supervision to all long distance phones. And with that answer supervision, the pricing of your long distance calls should be accurate. Not all long distance companies, however, choose to buy answer supervision (it costs a little more). And thus your long distance calls may still be billed inaccurately.

Check. If you are "accessing" your preferred long distance carrier by dialing a seven digit local number, then dialing your number and your account code, your carrier is probably not receiving Answer Supervision and the timing and billing of your long distance calls may be inaccurate. Check this out. Remember: just because your town has equal access doesn't mean your preferred long distance phone company has opted for it because it is expensive or for some other reason.

Virtually no hotels have answer supervision. So they start billing you arbitrarily. Some start billing you after three rings. Some after four. When you check out, carefully check your phone bill. You will, in most instances, find you have been billed for many uncompleted calls. Tell your family to pick up the phone quickly when you're out of town and may be calling them. Don't let the phone ring too many times as you're likely to be billed for the dubious pleasure of listening to ringing signals.

Answer supervision is getting better, however, as the electronics of "listening" to sounds on phone lines get better. Electronics are now available to do ” to a 95% accuracy ” what we as humans do ” to a 100% accuracy ” namely distinguish between a normal ringing sound, a fast busy sound and a person or fax machine answering the phone and saying "Hello." These electronics are getting better and less expensive, by the month. See Answer Supervision-Line Side.

Answer Supervision-Line Side

Answer Supervision-Line Side is a service I first read about in a US West publication, which describes it as "providing an electrical signal that is passed back to the originating end of a switched connection. This signal indicates that the called line has gone off-hook. This service offering has applicability for record start and end, announcement start and end, dialtone reorigination prevention, call progress sequence indications , and other uses. This service offering may be used by terminal equipment (PBX, pay telephone, call diverter, etc). connected to the calling line to determine that the call has been answered."


In data communications, answerback is a response programmed into a data terminal to identify itself when polled by a remote computer or terminal. This response is usually in reply to a Control-E (ASCII Character 5, Inquiry), which is known on the Telex and TWX networks as a "Who Are You?" character, or "WRU." The Answerback allows a remote computer to verify it has dialed correctly (usually on the Telex or TWX networks) by matching the Answerback received with the Answerback expected.

Answering Machine

A machine that answers your telephone when you don't. The machine plays a message that you have recorded to greet the caller, and then allows the caller to leave you a message. Reportedly, one of the first answering machines was developed in Sweden in the 1950s; it took about three days to install the beast . Answering machines largely are consumer items. They are not the same thing as voice mail. See also Voice Mail.

Answering Machine Detection

The ability of outbound dialing systems, inside of the host ACD, the PBX, or as part of the predictive dialer product, to detect and filter out calls answered by answering machines. These systems may place the associated telephone number in a callback (see Callback) queue and may also play a recorded message.

Answering Tone

The tone an asynchronous modem will transmit when it answers the phone. The tone indicates that it is willing to accept data.


  1. Access Network Termination.

  2. Alternate Number Translation. The ability to reroute 1-800 calls on NCP failure.

  3. An ant can lift 50 times its own weight, which is equivalent to a human being pulling a 10-ton trailer.

Ant Farm

Gigantic multiscreen movie theater complex with glass facade, often found near American malls. Also called multiplexes or gigaplexes. See Ant.


Advanced Networking Test Center. An FDDI interoperability testing center established in 1990.


Before the flood. Very old fashioned.


  1. In basic telecommunications, an antenna is a device for transmitting, receiving or transmitting and receiving radio frequency (RF) signals. The antenna ” its design, construction and placement ” is the most important part of any radio system. Antennas are designed for specific and relatively tightly defined frequencies and are quite varied in design. An antenna for a 2.5 GHz (MMDS) system does not work for a 28 GHz (LMDS) design. Antennas come in all shapes and sizes. Their shape depends on the frequency of the signal they're receiving or transmitting and the use to which their communications are being put to. Antennas can broadcast signals in all directions. They're called omnidirectional. They can also broadcast signals in a fine straight line ” like a flashlight. Electrical signals with frequencies higher on the spectrum, for example, are shorter and more directional. As they get higher on the spectrum, they look more like light. These must be focused and thus, require antennas which are shaped like the mirror reflector of a focusing flashlight. This parabolic shape focuses the broad beam (of the bulb or the electrical signal) into a narrow, focused beam. The weaker the received signal, the bigger the antenna must be. Antennas come in many varieties and have cute names, like parabola, cares- grain, helix , lens and horn. The plural of antenna is antennas. It used to be antennae. But then we all decided that antennae were for ants and antennas were for satellite and other telecommunications devices. See the following Antenna definitions.

  2. In RFID terminology, the antenna is the conductive element that enables the tag to send and receive data. Passive tags usually have a coiled antenna that couples with the coiled antenna of the reader to form a magnetic field. The tag draws power from this field.

Antenna Array

An assembly of antenna elements with dimensions, spacing, and illumination sequence such that the fields for the individual elements combine to produce a maximum intensity in a particular direction and minimum field intensities in other directions.

Antenna Beam

The radio frequency energy pattern emitted by an antenna. Imagine a flashlight. Turn the head one way and the light becomes more focused, and thus more intense . Now turn it the other and it becomes less focused. Radio and microwave antennas are designed to be less or more focused. A broadcast TV satellite will have an antenna whose beam covers the entire continental United States. A satellite like Iridium which needs to send individual signals to individual cellular-like phones will have tightly focused radio beams.

Antenna Blind Cone

The volume of space, usually approximately conical with its vertex at the antenna, that cannot be scanned by an antenna because of limitations of the antenna radiation pattern and mount. An example of an antenna blind cone is that of an air route surveillance radar (ARSR). The horizontal radiation pattern of an ARSR antenna is very narrow. The vertical radiation pattern is fan-shaped, reaching approximately 70 of elevation above the horizontal plane. As the antenna is rotated about a vertical axis, it can illuminate targets only if they are 70 or less from the horizontal plane. Above that elevation, they are in the antenna blind cone. Also called Cone of Silence.

Antenna Coupler

A device used to match the impedance of a transmitter and/or receiver to an antenna to provide maximum power transfer.

Antenna Dissipative Loss

A power loss resulting from changes in the measurable impedance of a practical antenna from a value theoretically calculated for a perfect antenna.

Antenna Effective Area

The functionally equivalent area from which an antenna directed toward the source of the received signal gathers or absorbs the energy of an incident electromagnetic wave. Antenna effective area is usually expressed in square meters. For parabolic and horn-parabolic antennas, the antenna effective area is about 0.35 to 0.55 of the geometric area of the antenna aperture.

Antenna Efficiency

Refers to the degree to which an antenna's power is radiated in relation to the power which is wasted in various losses.

Antenna Electrical Beam Tilt

The shaping of the radiation pattern in the vertical plane of a transmitting antenna by electrical means so that maximum radiation occurs at an angle below the horizontal plane.

Antenna Entrance

A pathway facility from the antenna to the associated equipment.

Antenna Feed

An antenna device which collects radio signals from space and puts them onto a coaxial line. See Feedhorn.

Antenna Gain

The ratio, usually expressed in decibels, of the power required at the input of a loss-free reference antenna to the power supplied to the input of the given antenna to produce, in a given direction, the same field strength, or the same irradiance, at the same distance. When not specified otherwise, the gain refers to the direction of maximum radiation. The gain may be considered for a specified polarization.

Antenna Illumination

The degree to which an antenna feed pattern covers an antenna reflector.

Antenna Lobe

A picture showing an antenna's radiation pattern. A more technical explanation: A three-dimensional radiation pattern of a directional antenna bounded by one or more cones of nulls (regions of diminished intensity).

Antenna Matching

The process of adjusting impedance so that the input impedance of an antenna equals or approximates the characteristic impedance of its transmission line over a specified range of frequencies. The impedance of either the transmission line, or the antenna, or both, may be adjusted to effect the match.

Antenna Noise Temperature

The temperature of a hypothetical resistor at the input of an ideal noise-free receiver that would generate the same output noise power per unit bandwidth as that at the antenna output at a specified frequency. The antenna noise temperature depends on antenna coupling to all noise sources in its environment as well as on noise generated within the antenna. The antenna noise temperature is a measure of noise whose value is equal to the actual temperature of a passive device.

Antenna Power Gain

An FCC term for "the square root of the ratio of the root- mean-square free space field intensity produced at one mile in a horizontal plane in micro- volts per meter for one kilowatt antenna input power 137.6 mV/m." This ratio may be expressed in dB.

Antenna Power Input

An FCC term for the RF peak or RMS power supplied to the antenna from its associated transmission line and matching network.

Antenna Structure

An FCC term which refers to the whole tower system including radiation system, supporting structure and any "surmounted appurtenances."


The plural of antenna ” the type that grow on ants ” is antennae. The plural of telecommunications antennas is antennas.


The process of giving human qualities to inanimate objects. For example, getting a file cabinet to talk about what's inside it, or getting a modem to explain how to do communications.

Anti Aliasing

See Antialiasing.

Anti Clockwise Polarized Wave

See Left-Hand Polarized Wave.

Anti Curl

A feature marketed by manufacturers of slimy paper fax machines (i.e. thermal paper). As the paper emerges from the fax machine, "anti-curl" simply sends the paper through a path which causes it to bend slightly in the opposite direction to which it was rolled over the roll. This bending purports to make the paper less curly when it emerges. It works to an extent. Virtually all slimy fax machines now have the anti curl "feature," though most don't advertise it, since it's like advertising that a fax machine makes faxes.

Anti Digit Dialing League

A group of people that resisted the move from named exchanges to all number dialing. The Bell System fought against the League because there was no global standardization between numbers and digits on rotary dial phones. Thus, IDDD was impossible until the advent of all digit numbers.

Anti Collision

An RFID term. A general term used to cover methods of preventing radio waves from one device from interfering with radio waves from another. Anti-collision algorithms are also used to read more than one tag in the same reader's field.

Anti Dilution

A private company is raising money. You buy shares. Part of the deal of buying shares is that you sign a "Shareholders Agreement" ” an agreement between you and the company. One clause in that Agreement says that if the company sells shares in the future at a price lower than you bought them, you will be issued additional shares. Let's say you buy 100 shares at $10. Then the company sells shares at $5. Then it must send you an additional 100 shares for free.

Anti Reflection Coating

A thin, dielectric or metallic film (or several such films ) applied to an optical surface to reduce its reflectance and thereby increase the transmittance of the optical fiber. The ideal value of the refractive index of a single layer film is the square root of the product of the refractive indices on either side of the film, the ideal optical thickness being one quarter of a wavelength.

Anti Replay

Security service where the receiver can reject old or duplicate packets in order to protect itself against replay attacks. IPSec (a group of Internet security measures) provides this optional service by use of a sequence number combined with the use of data authentication.

Anti Static

A material, such as packing material, that is treated to prevent the buildup of static electricity. The static charges gradually dissipate instead of building up a sudden discharge .

Anti Stuffing

A mechanical flap in a coin phone which prevents the blocking by paper or other material of coin chutes. An anti-stuffing flap is meant to assure that you, the user, get your money back after you've tried to make a call but didn't get through.

Anti Tromboning

A feature used when a call coming in a trunk is transferred back out to a trunk over the same physical link on which it arrived. A call in this state is said to be tromboned, and is consuming the expensive resource of two trunks. Transferring the call from its source to its new destination, and using no trunks is called anti-tromboning, a feature to prevent transfers from non-productively tieing up trunks. See also Tromboning.

Anti Viral Programs

Programs which scan disks looking for the tell-tale signatures of computer viruses.


  1. A filter (normally low pass) that band limits an input signal before sampling to prevent aliasing noise. See Aliasing Noise.

  2. A computer imaging term. A blending effect that smooths sharp contrasts between two regions of different colors. Properly done, this eliminates the jagged edges of text or colored objects and images appear smoother. Used in voice processing, antialiasing usually refers to the process of removing spurious frequencies from waveforms produced by converting digital signals back to analog.


Raising people's levels of anticipation and then disappointing them. A definition contributed by Gerald Taylor, president, of MCI.


A material, such as packing material, that is treated to prevent the buildup of static electricity. The static charges gradually dissipate instead of building up a sudden discharge.


See Anti tromboning.


Active Nonvolatile Memory. Memory that contains the software currently used by the network element.


Automotive Network Exchange: Private network service offering that originated as a collaborated commerce solution for automakers the world over.


  1. A term associated with IPv6, the proposed new protocol for the Internet, Anycast refers to the ability of a device to establish a communication with the closest member of a group of devices. By way of example, a host might establish a communication with the closest member of a group of routers for purposes of updating a routing table. That router would then assume responsibility for retransmitting that update to all members of the router group on the basis of a Multicast. Through this approach, the host is relieved of the mundane task of addressing each router in the network, a task clearly best accomplished by a lesser device with lesser responsibilities. See also IPv6. Compare with Broadcast, Multicast, and Unicast.

  2. In ATM, an address that can be shared by multiple end systems. An Anycast address can be used to route a request to a node that provides a particular service.


A high-speed local area network technology for which Hewlett-Packard Co. and International Business Machines Corp. created the original specifications. Announced in 1993, AnyLAN was intended to allow work groups operating Token Ring and Ethernet LANs to swap many more data- intensive applications at much greater speeds than possible at the time, increasing the speed and capacity of LANs sixfold to tenfold. HP and IBM announced they would give the technology of AnyLAN to any competitor free of charge, in order to establish it as a standard and expand the size of the total market. In 1996, the IEEE 802.12 committee officially recognized AnyLAN as the fast LAN standard, renaming it 100VG-AnyLAN. See 100VG-ANYLAN for a detailed explanation.


IBM product name for the ACF/VTAM feature that implements IBM's "Networking Blueprint" technology on hosts and OS/2 workstations and permits SNA LU 6.2 applications to work over TCP/IP or TCP/IP-oriented sockets applications to run over SNA.

Anytime Minutes

A term introduced by the cell phone business to mean minutes that could be used any time. Originally cell phones charged by minutes of usage ” often inbound and outbound. By the late 1990s, a bunch of bright marketing folks in the cell business had the idea to sell a bundle of minutes of usage for a flat price ” e.g. 200 minutes per month. They started selling "bundles" of cell phone monthly usage. The idea was to increase the money you got out of a subscriber each month. The hope was the customer wouldn't use up all the minutes. Most didn't. Typically the bundles included categories of minutes ” peak and non-peak. Eventually the non-peak minutes became unlimited and the peak minutes became "anytime" minutes. Anyway, the long and the short of it was that by the end of the 1990s, cell phone pricing became so complicated few mortals (i.e. you and me) could figure out which plan was the best for them. There were some gurus who claimed this was exactly what the cell phone companies had intended all along.

Anywhere Fix

The ability of a Global Positioning System (GPS) receiver to start position calculations without being given an approximate location and approximate time. See GPS.


Always On/Dynamic ISDN. ISDN is a set of standards for an digital, circuit- switched network. The standards specify several types of end user access circuits, each of which involves one or more B (Bearer) channels and one D (Data, or Delta) channel. The B channels are for circuit-switched user communications (voice, data, and video), and the D channels are primarily for signaling and control (e.g., on-hook and off-hook signaling, ringing signals, performance monitoring, synchronization and error control). As the signaling and control functions are not particularly intensive, there often is bandwidth available on the D channels. AO/DI takes advantage of that bandwidth, dynamically as it is available, for end user packet data transfer (e.g., e-mail transfer) between ISDN end users. For example, as much as 9.6 Kbps is available, on average, for packet data transfer over the 16-Kbps D channel associated with an ISDN BRI. AO/DI can be set up between the BRI circuit to your home and the PRI circuit to your office. Over the D channels, you can maintain a constant (always on) virtual connection from your home to your e-mail server. (That way you can hang out by the pool in Richardson, but still get your mail from the downtown Dallas office. Your boss in New York and your clients all over the world will think you're working hard at the office. Typical text e-mail works just fine at 9.6 Kbps. When more bandwidth is required for perhaps transferring an e-mail with a graphics attachment, one or more B channels can be activated automatically. Not all service provider offer AO/DI. Those that do price it pretty attractively. See also ISDN.


See Angle of Arrival.


Advice Of Charge. See Advice of Charge.


Administrative Operating Company Number. Among the provisions of the Telecommunications Act of 1996 was the requirement that the RBOC's (Regional Bell Operating Companies') Code Administrators no longer work with Bellcore (now Telcordia Technologies) in the administration of NPA (Numbering Plan Administration, i.e., area codes) and NXX (Central Office prefixes) administration. To fill the void, a small number of AOCN companies were authorized to assume this responsibility. Each LEC (Local Exchange Carrier), whether ILEC (Incumbent LEC) or CLEC (Competitive LEC) must select an authorized AOCN to input various data into the various Traffic Routing Administration (TRA) tables to make sure that calls are properly routed through the PSTN (Public Switched Telephone Network), and that the traffic is properly rated. About the same time, Telcordia's role as NANPA (North American Numbering Plan Administrator) was shifted to Martin Marietta. See also CLEC, ILEC, LEC, NANPA, NNX, OCN, PSTN, and TRA.


America OnLine Hell. Hacker programs that allow one to mess with AOL's software. Using these programs you can get access to, inter alia, personal electronic mail accounts.


See America Online.


Alternate Operator Services. Today there are many Operator Services Providers not owned by the Bell Telephone Companies or AT&T. The AOS industry is dropping the descriptive term "alternate" and communicating that they be known as OSPs. AOS was coined by AT&T. See AOSP and Operator Service Providers.


Alternate Operator Service Provider. A new breed of long distance phone company. It handles operator-assisted calls, in particular Credit Card, Collect, Third Party Billed and Person to Person. Phone calls provided by OSP companies are typically far more expensive than phone calls provided by "normal" long distance companies, i.e. those which have their own long distance networks and which you see advertised on TV. You normally encounter an OSP only when you're making a phone call from a hotel or hospital phone, or a privately-owned payphone. It's a good idea to ask the operator the cost of your call before you make it.


Auxiliary Operator Services System Voice Response.


Asia and Oceania Workshop. One of the three regional OSI Implementors' Workshops.


  1. See ADD-ON or Applications Processor. AP is an AT&T word for a piece of equipment which hangs off the side of their PBX and makes it do more things, like voice mail.

  2. See Adjunct Processor, an AIN term for a decentralized SCP. See Adjunct Processor.

  3. Access Providers.

  4. Anomalous Propagation.


All Points Addressable. A method of host graphics implementation which uses vertical and horizontal pixel coordinates to create a more graphic image. An SNA definition.


The web server software on about half of the world's existing web sites is Apache. Apache is UNIX freeware. Apache was originally based on code and ideas found in the most popular HTTP server of the time: NCSA httpd 1.3. It has since evolved into a far superior system that can rival ” some say surpass ” any other UNIX-based HTTP server in terms of functionality, efficiency, and speed. Apache includes several features not found in the free NCSA server, among which are highly configurable error messages, DBM- based authentication databases, and content negotiation. It also offers dramatically improved performance and fixes many bugs in the NCSA 1.3 code.


Asynchronous Packet Assembler/Disassembler.


Adaptive Predictive Coding. A narrowband analog-to-digital conversion technique employing a one-level or multilevel sampling system in which the value of the signal at each sample time is adaptively predicted to be a linear function of the past values of the quantized signals. APC is related to linear predictive coding (LPC) in that both use adaptive predictors. However, APC uses fewer prediction coefficients, thus requiring a higher bit rate than LPC.


The American Public Communications Council, which is part of the North American Telecommunications Association (NATA).


Association of Public-Safety Communications Officials International, Inc. An organization dedicated to the enhancement of public safety communications. APCO's more than 13,000 members come from public safety organizations including 911 centers, law enforcement agencies, emergency medical services, fire departments, public safety departments, military units, and colleges and universities.


APCO Project 25. A voluntary "standard" for a Common Air Interface (CAI) for SMR (Specialized Mobile Communications) public service networks in the US. APCO25 is a joint effort of APCO (Association of Public-Safety Communications Officials International Inc.) and NASTD (National Association of State Telecommunications Directors) for a uniform digital mobile radio technology. Representatives of the NTIA (National Telecommunications Industry Association), NCS (National Communications System), and DOD (Department of Defense) also sit on the steering committee. APCO25 makes use of channels of 6.24 kHz and 12.5 kHz, supporting aggregate bit rates of 9600 bps for data communications. Voice is supported at 4,400 bps. See also APCO, SMR, and TETRA.


Avalanche PhotoDiode. A diode that, when hit by light, increases its electrical conductivity by a multiplication effect. APDs are used in lightwave receivers because the APDs have great sensitivity to weakened light signals (i.e. those which have traveled long distances over fiber). APDs are designed to take advantage of avalanche multiplication of photocurrent.

Aperiodic Antenna

An antenna designed to have an approximately constant input impedance over a wide range of frequencies; e.g., terminated rhombic antennas and wave antennas.


For a parabolic reflector or a horn antenna, aperture is the dimension of the open mouth and represents a surface over which it is possible to calculate the radiation pattern. For a series of n stacked transmitting elements such as dipoles or slots, the vertical aperture is usually defined as n times the element spacing in wavelengths.

Aperture Distortion

In facsimile, the distortions in resolution, density, and shape of the recorded image caused by the shape and finite size of the scanning and recording apertures or spots.

Aperture Grille

A type of monitor screen made up of thin vertical wires. Said to be less susceptible to doming than iron shadow mask.


Application Programming Interface. Software that an application program uses to request and carry out lower-level services performed by the computer's or a telephone system's operating system. For Windows, the API also helps applications manage windows, menus , icons, and other GUI elements. In short, an API is a "hook" into software. An API is a set of standard software interrupts, calls, and data formats that application programs use to initiate contact with network services, mainframe communications programs, telephone equipment or program-to-program communications. For example, applications use APIs to call services that transport data across a network. Standardization of APIs at various layers of a communications protocol stack provides a uniform way to write applications. NetBIOS is an early example of a network API. Applications use APIs to call services that transport data across a network.


An ATM term. Native ATM Application Program Interface Connection: API_connection is a relationship between an API_endpoint and other ATM devices that has the following characteristics:

  1. Data communication may occur between the API_endpoint and the other ATM devices comprising the API_connection.

  2. Each API_connection may occur over a duration of time only once; the same set of communicating ATM devices may form a new connection after a prior connection is released.

  3. The API_connection may be presently active (able to transfer data), or merely anticipated for the future.


Automatic Program Load in telecom. In data processing, it's a popular programming language.


Advanced Private Line Termination. Provides the PBX user with access to all the services of an associated enhanced private switched communications services (EPSCS) network. it also functions when associated with a common control switching arrangement (CCSA) network. See Advanced Private Line Termination.


  1. Average Positions Manned, the average number of ACD positions manned during the reporting period for a particular group.

  2. Advanced Power Management. A specification originally sponsored by Intel and Microsoft to extend the life of batteries in battery-powered computers. The idea of the specification is for the application programs, the system BIOS and the hardware to work together to reduce power consumption. An APM-compliant BIOS provides built-in power management services to the operating system of your PC. The operating system passes calls and information between the BIOS and the application programs. It also arbitrates power management calls in a multi-tasking environment (such as Windows) and identifies power-saving opportunities not apparent to applications. The application software communicates power-saving data via predefined APM interfaces. Windows 95 adopted APM to shut down the computer. It uses a special mode of the latest Intel processors ” System Management Mode, or SMM. SMM lets the BIOS take control of the machine at any time and manage power to peripherals. A BIOS' APM support can't be circumvented by other software. This could cause a crash. Microsoft, Intel, Toshiba and others are now working on a new spec, called ACPI ” Advanced Configuration and Power Interface. and www.ata.or/~acpi/.


Asia Pacific Network Information Center. A group formed to coordinate and promote TCP/IP based networks in the Asia-Pacific region. APNIC is responsible for management and assignment of IP (Internet Protocol) addresses in the Asia-Pacific, just as are ARIN and RIPE in the regions of the Americas and Europe, respectively. See also ARIN, IP, and RIPE.


Adaptive Performance Optimization. A technology used on the Texas Instruments ThunderLAN chipset, which was jointly developed by Compaq and Texas Instruments. APO dynamically adjusts critical parameters for minimum latency, minimum host CPU utilization and maximum system performance. This technology ensures that the capabilities of the PCI interface are used for automatically tuning the controller to the specific system in which it is operating.

Apocalypse, Four Horsemen Of

The four horsemen of the Apocalypse were War, Plague, Famine and Death.

Newton[ap]s Telecom Dictionary
Newton[ap]s Telecom Dictionary
ISBN: 979387345
Year: 2004
Pages: 133 © 2008-2017.
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