ABF-Access Code


See Air Blown Fiber.


Optical memory data writing technique in which a laser burns holes (or pits) into thin metal film.


Asynchronous Balanced Mode. A service of the data link level (Logical Link Control) in IBM's token-passing ring. ABM operates at the Systems Network Architecture data link control level and allows devices to send data link commands at any time.


ABNormal alarm status.

Abnormal Release

A condition that occurs when your cellular telephone connection is interrupted unexpectedly. An abnormal release can occur due to a switching error, a failed handoff , or any number of other reasons. The cellular providers came up with the term "abnormal release." It's a good thing that they didn't call it "unusual release," because it's not all that unusual.


Ameritech Bell Operating Company. Beth Sullivan, a reader, emails me one morning. She's desperate. She has a job to do...and there's one stupid acronym impeding her productivity ” ABOC. She's convinced it's something to do with some complex technical thing she should know and will look stupid if she doesn't know. I check all my sources. No luck. She emails me the following morning. Mystery solved : Ameritech Bell Operating Company. the irony of all this? It's not even the company's name. The company's real name is SBC Ameritech Corporation.


To stop doing something. Often to get out of a software program. Also, to discontinue sending or receiving a message.

Abort Delimiter

A local area network term. A signal sent by a Token Ring station indicating that the message it was sending was terminated part way through the transmission, and is known to be incomplete. The station will then increment the soft error counter for Abort Delimiter Transmitted, and send a soft error report within two seconds.

Abort Sequence

A series of 12 to 18 1-bits appearing at the end of an AppleTalk LLAP frame. The sequence delineates the end of the frame.

Above 890 Decision

The 1959 FCC decision which allowed companies to build their own private microwave communications systems. The decision resulted from AT&T Long Lines' reluctance to provide companies with long distance service to remote places, such as oil wells, gas pipelines, power stations and paper plants. The decision got its name because the FCC allowed privately-owned microwave systems using radio frequencies "above 890" megahertz ” which are naturally called "microwave." See also Microwave and ENTELEC.

Above The Line

Expenses incurred by telephone company that are charged to the ratepayer by being allowed in the company's rate-base.


  1. Available Bit Rate. As defined by the ATM Forum, ABR is an ATM layer service category for which the limiting ATM layer transfer characteristics provided by the network may change subsequent to connection establishment. A flow control mechanism is specified which supports several types of feedback to control the source rate in response to changing ATM layer transfer characteristics. It is expected that an end-system that adapts its traffic in accordance with the feedback will experience a low cell loss ratio and obtain a fair share of the available bandwidth according to a network specific allocation policy. Cell delay variation is not controlled in this service, although admitted cells are not delayed unnecessarily. In short, ABR provides for transport of traffic at the bit rate available at the time, and on a dynamic basis.

  2. Area Border Router. Router located on the border of one or more OSPF areas that connects those areas to the backbone network. ABRs are considered members of both the OSPF backbone and the attached areas. They therefore maintain routing tables describing both the backbone topology and the topology of the other areas.


AutoBaud Rate Detect. A process by which a receiving data device determines the speed, code level, and stop bits of incoming data by examining the first character ” usually a preselected sign-on character (often a carriage return). ABR allows the receiving device to accept data from a variety of transmitting devices operating at different speeds without needing to establish data rates in advance.

Abrasion Resistance

Ability of material or cable to resist surface wear.

Abrupt Close

Close of a connection on a network without any attempt to prevent any loss of data.


  1. See Average Busy Season.

  2. Alternate Billing Services. These are IN (Intelligent Network) services that allow subscribers to charge a call to a number or telephone other than the one they are using. For example, by using a charge card, credit card or personal identification number.

  3. Application Bridge Server. Software module that allows the ICM to share the application bridge interface from an Aspect ACD with other applications.

Absent Subscriber Service

A service offered by local telephone companies to subscribers who will be away. A live operator or a machine intercepts the calls and delivers a message. When you come back, you get your old number. But in the meantime, while you're away, you pay less money per month than you would for normal phone service. Also known as Vacation Service.


A horizontal coordinate.

Absolute Delay

The time interval or phase difference between transmission and reception of a signal.

Absolute Gain

In simple language, absolute gain measures how much a device improves the power of a signal. The absolute gain of an antenna, for a given direction and polarization, is the ratio of (a) the power that would be required at the input of an ideal isotropic radiator to (b) the power actually supplied to the given antenna, to produce the same radiation intensity in the far-field region. If no direction is given, the absolute gain of an antenna corresponds to the direction of maximum effective radiated power. Absolute gain is usually expressed in dB. See Isotropic, Gain.

The absolute gain of a device is the ratio of (a) the signal level at the output of the device to (b) that of its input under a specified set of operating conditions. Examples of absolute gain are no-load gain, full-load gain, and small-signal gain.

Absolute URL

A URL that contains a scheme (for example, http) and a server address, for example www.harrynewton.com.

Absolute Zero

A temperature about 460 degrees below zero in Fahrenheit.


Attenuation (reduction in strength of a signal) caused by dissipation of energy. In the transmission of electrical, electromagnetic, or acoustic signals, absorption is the conversion of the transmitted energy into another form, usually thermal. Absorption is one cause of signal attenuation. The conversion takes place as a result of interaction between the incident energy and the material medium, at the molecular or atomic level.

Absorption Band

A spectral region in which the absorption coefficient reaches a relative maximum, by virtue of the physical properties of the matter in which the absorption process takes place.

Absorption Coefficient

A measure of the attenuation caused by absorption of energy that results from its passage through a medium. Absorption coefficients are usually expressed in units of reciprocal distance. The sum of the absorption coefficient and the scattering coefficient is the attenuation coefficient.

Absorption Index

A measure of the attenuation caused by absorption of energy per unit of distance that occurs in an electromagnetic wave of given wavelength propagating in a material medium of given refractive index.

Absorption Loss

That part of the transmission loss caused by the dissipation or conversion of electrical, electromagnetic, or acoustic energy into other forms of energy as a result of its interaction with a material medium.

Absorption Modulation

Amplitude modulation of the output of a radio transmitter by means of a variable-impedance circuit that is caused to absorb carrier power in accordance with the modulating wave.

Abstract Syntax

In open systems architecture, the specification of application- layer data or application-protocol control information by using notation rules that are independent of the encoding technique used to represent the information.

Abstract Syntax Notation One

(ASN.1). LAN "grammar," with rules and symbols, that is used to describe and define protocols and programming languages. ASN.1 is the OSI standard language to describe data types. More formally , ASN.1 is a standard, flexible method that (a) describes data structures for representing, encoding, transmitting, and decoding data, (b) provides a set of formal rules for describing the structure of objects independent of machine-specific encoding techniques, (c) is a formal network-management Transmission Control Protocol/Internet Protocol (TCP/IP) language that uses human-readable notation and a compact, encoded representation of the same information used in communications protocols, and (d) is a precise, formal notation that removes ambiguities .


Advanced Broadcast Television.


  1. Access Customer.

  2. See AuC, Authentication Center.

  3. Alternating Current. Typically refers to the 120 volt electricity delivered by your local power utility to the three-pin power outlet in your wall. Called "alternating current" because the polarity of the current alternates between plus and minus, 60 times a second. In an AC power system, current (AMPS) is delivered to a load through a wire called the "hot" wire and returns through a wire called the "neutral" wire. The other form of electricity is DC, or direct current, in which the polarity of the current stays constant. Direct current, for example, is what comes from batteries. Outside North America, electricity typically alternates at 50 times a second ” which is neither better nor worse , just different. In North America, standard 120 volt AC may be also be referred to as 110 volts, 115 volts, 117 volts or 125 volts. Con Edison, the electricity supplier to New York City, told me that they are only obliged to deliver voltage to 120 volts plus or minus 10%. This means your outlet may deliver anywhere from 118 volts to 132 volts before your power company will get concerned . But you probably should. Telephone and computer are sensitive to voltage fluctuations ” some more to high voltages; some more to low voltages. My suggestion: If your stuff is valuable , protect it with a voltage regulator . Or better, power it with stable DC current, which you've converted from fluctuating AC power.

Your AC electrical circuit consists of two supply conductors ” hot and neutral. There is also a "load." That is the term for the device you're running. The hot, energized or live conductor is ungrounded and delivers energy to the load. The hot conductor is connected to the fuse or circuit breaker at the main service entrance . The neutral or common conductor is grounded and completes the circuit from the load back to the utility transformer. The load is any electric or electronic appliance or gadget plugged into the AC electrical outlet. It completes the circuit from the transformer through the hot conductor, to the load, through the neutral conductor and back to the utility transformer. Standard 120 volt circuits also include an equipment ground conductor. This equipment grounding conductor provides an intended path for fault current and is never intended to be a part of the load circuit. The equipment ground serves three very important purposes:

  1. It maintains metal appliance cases at zero volts, thus protecting people who touch the cases from receiving an electrical shock .

  2. It provides an intentional fault path of low impedance path for current flow when the hot conductor contacts equipment cases (ground fault). This current causes the fuse or circuit breaker to open the circuit to protect people from electric shock.

  3. Any electronic equipment (not electrical) uses the equipment ground as a zero volt reference for logic circuits to provide proper equipment performance.

This is a true story: Thomas Edison helped develop the electric chair in order to " prove " the " deadly dangers" of alternating current (AC) electrical systems. Edison was in direct competition with Westinghouse's brilliant Nikola Tesla, whom he detested, and whose efficient AC system was rapidly becoming the preferred method for transmission of electricity over long distances. This threatened Edison's direct current (DC) system. Realizing he was losing the war, Edison began holding demonstrations in which he electrocuted large numbers of dogs and cats by luring them onto a metal plate wired to a 1,000-volt AC generator. This display, although it attracted people, did not work to sway the public to his side and the AC system became the electricity standard. The legacy of all of Edison's efforts directly led to the development of the electric chair, which uses AC electricity.

See AC Power, Grounding, Battery and Surge Arrestor.

AC Field

The Access Control field of a token. See Token.

AC Power

Phone systems typically run on AC, Alternating Current. Except for very small systems, phone systems typically need their own dedicated (i.e., shared with no other device) AC power line. This line should be cleaned" with a power conditioner, or voltage regulator. It also should be protected with a surge arrestor. If possible, the phone system should also be protected by a battery-based UPS (Uninterruptible Power Supply). The most reliable battery backup is lead acid, the same technology as used in your car. Phone systems consume more power as they process more phone calls. For example, a PBX brochure says that at minimum capacity it needs less power than eight 100-watt light bulbs, but that at its maximum duplex capacity it needs the same power as 26 100-watt light bulbs ” or 2600 watts. Telephone sets typically draw their power from the central telephone switch, be it a PBX or a central office. Few phones require their own AC power. ISDN devices and phones typically require a local AC power source. See AC, Ground and Grounding.

AC To DC Converter

An electronic device which converts alternating current (AC) to direct current (DC). Most phone systems, computers and consumer electronic devices (from answering machines to TVs) run on DC. Most phone systems have an AC to DC converter in them. Hint: it's probably buried in the power supply.

AC-DC Ringing

A type of telephone signaling that uses both AC and DC components ” alternating current to operate a ringer and direct current to aid the relay action that stops the ringing when the called telephone is answered .


AC15 is a British protocol for signaling on private wires between analog switches.


  1. Automatic Circuit Assurance.

  2. Australian Communications Authority. The regulatory authority for telecommunications and radiocommunications, established under the Australian Communications Authority Act 1997. See ACIF and ACCC.

  3. Account Customer Address.

Academic Computing Research Facility Network

ACRFNET. A network connecting various research units such as colleges and research and development laboratories in the U.S.


A network within Russia which connects universities.


ARINC Communication Addressing Reporting System, airline system developed at VHF and also implemented in aeronautical satellite communications systems. See ARINC.


Additional Cooperative Acceptance Testing. A method of testing switched access service that provides a telephone company technician at the central office and a carrier's technician at its location, with suitable test equipment to perform the required tests. ACAT may, for example, consist of the following tests:

  • Impulse Noise

  • Phase Jitter

  • Signal-to-C-Notched Noise Ratio

  • Intermodulation (Nonlinear) Distortion

  • Frequency Shift (Offset)

  • Envelope Delay Distortion

  • Dial Pulse Percent Break


  1. Annoyance Call Bureau.

  2. Automatic Call Back.


Analog Control Channel. A wireless term. The ACC is the analog signaling and control channel used in some cellular systems in support of call setup and certain features. Defined in IS-54B, the ACC is a radio frequency channel distinct from those used to support conversations in some systems using TDMA (Time Division Multiple Access). A DCCH (Digital Control CHannel) is preferred, for obvious reasons of error performance; the DCCH is specified in IS-136, the successor to the IS-54 series. See IS-54B and IS-136.


The Australian Competition and Consumer Commission is an independent statutory authority which administers Trade Practices Act 1974 and the Prices Surveillance Act 1983. It claims to be the only national government agency in Australia responsible for enforcing the competition aspects of the Trade Practices Act.

Accelerated Aging

A series of tests performed on material or cable meant to duplicate long term environmental conditions in a short period of time. Such tests might include exposure to extreme cold, heat, variations in humidity (including "wet"), and mechanical stress. Also refers to the impact of the stress associated with revising and maintaining Newton's Telecom Dictionary, according to Ray Horak, Consulting Editor.

Accelerated Depreciation

A method which allows greater depreciation charges in the early years of an asset's life and progressively smaller ones later on. The total amount of depreciation charged is still equal to 100% of the asset's value. By taking the charges early on in the asset's life, you get the time value of money, i.e. depreciation charged today (and tax saved today) is worth more than the same amount of depreciation charged (or tax saved) tomorrow.

Accelerated Graphics Port

See AGP.


  1. A chemical additive which hastens a chemical reaction under specific conditions. A term used in the telecommunications cable manufacturing industry.

  2. In a Windows program, an accelerator is a keystroke that dispatches a message to a program, invoking one of its functions. For example, Alt-F4 tells the current Windows application of Windows itself to quit.

Accelerator Board

A board added onto a personal computer's main board and designed to increase the PC's performance in writing to screen or disk, etc. See also Accelerator Card.

Accelerator Card

An Apple term for an add-on product that upgrades the CPU of a Macintosh to a higher speed or more powerful generation of processor. An accelerator card is usually a " daughter board" that clips onto the original CPU or is inserted into the socket that held the original CPU. You need an accelerator card to use virtual memory or enhanced 24-bit addressing on LC, Mac Plus, SE and Classic. See Accelerator Board.


Accenture is the new name for Anderson Consulting. I have no idea why they changed their name. According to Accenture, the firm is reinventing itself to become the market maker, architect and builder of the new economy, bringing innovations to improve the way the world works and lives.

Acceptable Angle

The biggest possible angle between a ray and the center axis. The maximum angle that a fiber optic cable accepts light for further transmission.

Acceptable Use Policy

AUP. Many transit networks have policies which restrict the nature of their use or the basis on which access privileges are granted. A well known example is that of the now defunct NSFNET's (National Science Foundation NETwork) AUP which traditionally did not allow commercial use. Subsequently, of course, NSFNET did become commercialized as the Internet. AUP enforcement varies with the specific network.


  1. A formal set of criteria which you and your vendor define and agree upon that will determine whether the system he shipped you and/or installed at your place is now as you both agreed upon, and therefore, you are obligated to pay for it. See Acceptance Test.

  2. Acceptance also refers to the amount of time within which a buyer has to decide whether a software or hardware element is acceptable. Different from a warranty on performance, acceptance applies to the appearance and performance of the element as initially configured and installed, and as compared to the specifications to which the seller and purchaser have agreed. Acceptance periods usually range from two to four weeks, but are determined on a case-by-case basis. It's commonly used in the secondary telecom equipment marketplace , as well. See Acceptance Test.

Acceptance Angle

The angle over which the core of an optical fiber accepts incoming light. It's usually measured from the fiber axis.

Acceptance Cone

In fiber optics, the cone within which optical power may be coupled into the bound modes of an optical fiber. The acceptance cone is derived by rotating the acceptance angle about the fiber axis.

Acceptance Pattern

Of an antenna, for a given plane, a distribution plot of the off-axis power relative to the on-axis power as a function of angle or position. The acceptance pattern is the equivalent of a horizontal or vertical antenna pattern. The acceptance pattern of an optical fiber or fiber bundle is the curve of total transmitted power plotted against the launch angle.

Acceptance Test

The final test of a new telephone system. If the system passes the test ” i.e. it meets all specifications laid down in the sales contract ” and is working well, then, and only then, will the customer finish paying for it. See also Acceptance and Acceptance Testing.

Acceptance Testing

Operating and testing of a communication system, subsystem, or component, to ensure that the specified performance characteristics have been met. See Acceptance and Acceptance Test.

Acceptance Trial

A military term. A trial carried out by nominated representatives of the eventual military users of the weapon or equipment to determine if the specified performance and characteristics have been met.


The Bluetooth device receiving an action from another Bluetooth device. The device sending the action is called the initiator. The acceptor is typically part of an established link. See Bluetooth.


A series of digits or characters which must be dialed , typed or entered in some way to get use of something. That "something" might be a PBX or KTS telephone system, a long distance carrier, an electronic mail service, a private corporate network, a mainframe computer, or a local area network. Once the user dials the main number for the service he must then enter his assigned Access Code to get permission to use the system. An Access Code becomes an Authorization Code when it is used for identifying the caller; it becomes an Account Code when used for purposes of identifying the client for billback of associated charges. Access Code may also mean the digit, or digits, a user must dial to be connected to an outgoing trunk. For example, the user picks up his phone and dials "9" for a local line, dials "8" for long distance, dials "76" for the tie line to Chicago, etc. In programming a phone system there are unique Access Codes for Startup, Configuration programming, Administration programming and other functions; technicians who have been certified at various levels are provided with the appropriate Access Codes which allow them to invoke the appropriate level of system privilege.

Access Attempt

The process by which one or more users interact with a telecommunications system to start to transfer information. An access attempt begins with an issuance of an access request by an access originator. An access attempt ends either in successful access or in access failure.

Access Bus

Access Bus is correctly spelled Access.bus. It is a 100 Kbps bus currently being implemented as part of the Video Electronics Standards Association's Display Data Channel for controlling PC monitors . Access.bus allows bidirectional communication between compatible systems and displays, allowing on-the-go installation. Also supports daisychaining to reduce cable snarl. Access.bus has four pins per connector. See also USB and Firewire.

Access Channel Capacity

Cable television channel capacity dedicated to cablecasting by entities not affiliated with the cable system operator, and over which the cable system operator does not exercise editorial control. Categories of access channel capacity are:

  • Public Access, dedicated for use by the general public.

  • Educational Access, dedicated to local educational authorities.

  • Government Access, dedicated to local government.

  • Leased Access, dedicated to commercial users.

The significant distinction here is "editorial control": subject to certain narrowly-defined exceptions (obscenity, " unlawful conduct"), the cable operator is prohibited from exercising editorial control over programming carried on access channels. This distinction affects the records which must be kept in the system's PIF:

  • The operator is exempt from the requirements of Section 76.225c of the FCC rules regarding limits on commercial matter in children's programming carried on access channels.

  • The operator is required by Section 76.701(h) to maintain records to verify compliance with rules governing leased-access channels carrying indecent programming.

Access Charge

As part and parcel of the Modified Final Judgement (MFJ) which mandated the breakup of the Bell System though AT&T's divestiture of the Bell Operating Companies, the FCC declared that all end users have easy access to the long distance carrier of their choice. Further, such access to the InterExchange Carrier (IEC, or IXC) was to be provided with equal ease, i.e. on an equal 1+ basis, as traditionally enjoyed by AT&T alone. Additionally, the breakup of the Bell System invalidated the complex settlements structure which served to subsidize the Local Exchange Carriers (LECs) for providing local access to the long distance network(s). In order to replace the traditional settlements process and to compensate the LECs for the use of the vital , expensive and relatively unprofitable local access network, Access Charges were mandated , falling into two general categories.

  1. The end user Access Charge, also known as Customer Access Line Charge (CALC) applies to every local loop, and is sensitive to the nature of the circuit. Subject to review and adjustment by the FCC on an annual basis, such Access Charges differ for residential and business users, single lines versus trunks, leased lines versus local access circuits, and so on. A mandatory charge appearing as a separate line item on the user's bill, it applies whether or not the user ever, in fact, places a long distance call over either a wired or wireless network. This surcharge is levied per the Code of Federal Regulations, Title 47, Part 69.

  2. The Carrier Access Charge (CAC) applies to all IXCs which connect to the LEC network. Paid by the IXC to the LEC, such charges are determined by special tariffs subject to regulatory approval, and are sensitive to factors including the distance between the IXC Point of Presence (POP) and the point of termination into the LEC network. Additionally, the IXC pays to the LEC a usage charge sensitive to the traffic passed to the IXC as measured by Minutes of Use. The Telecommunications Act of 1996 greatly modifies the basis on which such charges are determined and levied. Most especially , the act eliminates such charges to the extent that the IXCs provide local exchange service directly, effectively bypassing the incumbent LECs.

Access Code

A series of digits or characters which must be dialed, typed or entered in some way to get use of something. That "something" might be the programming of a telephone system, a long distance company, an electronic mail service, a private corporate network, a mainframe computer, a local area network. Once the user dials the main number for the service he must then enter his assigned Access Code to get permission use the system. An Access Code becomes an Account Code when it is used for identifying the caller and doing the billing. Access Code may also mean the digit, or digits, a user must dial to be connected to an outgoing trunk. For example, the user picks up his phone and dials "9" for a local line, dials "8" for long distance, dials "76" for the tie line to Chicago, etc. In programming a phone system such as Nortel Networks' Norstar, there are Access Codes to begin Startup, Configuration programming, and Administration programming.

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

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