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Abbreviated dialing – The ability of a telephone user to reach frequently called numbers by using less than seven digits. Synonym: Speed Dialing. Access – (1) Point at which entry is gained into a circuit or a network. May be switched or dedicated. (2) Ability to obtain data from a storage device or peripheral. (3) Type of connection between CPE and network. Access charge – A fee paid by long-distance carriers to local telephone companies for use of local facilities, and by telephone subscribers to obtain access to local networks. Access code – Preliminary digits a user is required to dial to be connected to a particular trunk group, channel or line. (2) A short sequence of digits allowing a user to access a specific facility, service, feature or function of a telecommunications network or computer system. Access control – (1) Action taken to permit ordinary use of the components of a communications system. (2) The tasks performed by hardware, software and administrative controls to monitor system operation, ensure data integrity, perform user identification, record system access and changes and grant users access. Access line – A circuit between a subscriber and a switching center. Any line giving access to a larger system or network. Also, the private lines feeding a common control switching arrangement or enhanced private switched communications service switch from a PBX. access method – (1) A technique for moving data, voice or video between main storage and input/output devices. (2) In local area networks, the technique and/or program code used to determine use of the communications medium by granting access selectively to individual stations. Account – Within billing terminology, this represents a customer’s product or service location. Account code – Two-digit code associated with an authorization code, identifying the caller. Acknowledge character (ack) – A transmission control character transmitted as an affirmative response to a connecting station or to a sender. [May also be used as an accuracy control character.] Acoustic coupler – A special type of modem that converts acoustic energy (sound waves) into electrical energy, allowing a standard telephone handset to be attached to a computer or data terminal for data transmission. Adaptive transform coding – An audio coding algorithm. Address – (1) In a communications network, the identifying designation of an entity that is physically and/or logically distinct. (2) The destination of a message. (3) In software, a location that can be specifically referred to in a program. It can refer to a storage location, a terminal, a peripheral device, a cursor location or any other unit or component in a computer network. Alarm – A visual or audio signal which signifies that an error has occurred or an abnormal condition exists. Algorithm – A prescribed set of well-defined rules for the solution of a problem in a finite number of steps. For example a full statement of an arithmetic procedure for evaluating sine x to a stated precision. All trunks busy (ATB) – A single tone interrupted at a 120 impulses per minute (ipm) rate to indicate all lines or trunks in a routing group are busy. Allocate – To assign a resource for use in performing a specific task. Alpha test – The stage during the research and development of a new product during which a prototype of the system is operated to determine whether the system concept and design are functional. Stage to identify areas that need further development and/or enhancement. Alpha-geometric – A high resolution videotex display technique. [Pictures are created by instructions such as draw a line, draw a circle, fill in an area. Picture definition is dependent upon the resolution capability of the display terminal.] Alpha-mosaic – A low resolution block-oriented videotex display technique. Picture definition is fixed at 64 by 60 elements, or pixels, no matter what the resolution capability of the display terminal. Alternate route – A secondary communications path used to reach a destination if the primary path is unavailable. Alternate voice data (AVD) – A single transmission facility which can be used for either voice or data. American Standard Code for Information Interchange (ACSII) – A code with seven information signals plus one parity check signal, designed for interworking between computers (i.e., the transmittal of text). The most popular coding method used by computers for converting letters, numbers, punctuation and control codes with digital form. Amplifier – (1) Device which receives an input signal in wave form and outputs a magnified signal. (2) Electronic device used to increase signal power or amplitude. Analog – A transmission method employing a continuous (rather than pulsed or digital) electrical signal that varies in amplitude or frequency in response to changes of sound, light, position, etc., imposed on a transducer in the sending device; opposite of digital. Analog signal – A signal in the form of a continuous varying physical quantity such as voltage -which reflects variations in some quantity; or loudness in the human voice as opposed to digital. Answerback – A signal sent by a data receiver to a data transmitter indicating it is ready to receive data, or is acknowledging the receipt of data. [The answerback is typically part of the “handshaking” between devices.] Answer supervision – (1) An off-hook signal indicating when the called party answers; used to read calls for billing purposes. (2) A signal generated by the originating switch (hardware answer supervision) or by the switch which terminates the call (software answer supervision, when FGA or WATS is used to terminate the call). Append – To change or alter a file or program. Application layer – The top layer of the OSI seven-layer logical structure for data services; the end-user layer. Applications software – The instructions that direct the hardware to perform specific functions. Common software applications include payroll, inventory control and electronic spreadsheets. Architecture – The interaction between hardware and software in a computing system to achieve the most economic, efficient, secure, rapid or low-maintenance system. Archive – A procedure for transferring information from an on-line storage diskette or memory area to an off-line storage medium. Area code – The three-digit numbering plan area code in North America which permits direct distance dialing on the telephone system. [The first digit is never 1 or 0, and the second digit is always 1 or 0.] Synonym: Numbering Plan Area (NPA). Artificial intelligence – The capability of a computer to perform functions that are normally associated with human intelligence, such as reasoning, learning or self-improvement. Assembler – (1) A program capable of translating assembly code into digit code. The first major step in the automation of software development. Permitting symbolic (i.e., named) references to storage locations, rather than requiring the use of numbers, and eliminating the necessity to program in binary or other machine language. Synonym: assembly program. Assembly code – Programming language with statements that may be instructions or declarations. The instructions usually have a one-to-one correspondence with machine instructions. Assign – To give a new value to a variable during the running of a program. Asterisk laws – Gives consumers the right to say they don’t want to receive marketing phone calls by choosing to have an asterisk next to their names in the telephone book. The asterisk means “no phone solicitations.” Asynchronous computer – A computer in which each operation starts as a result of a signal generated by the completion of the previous operation, or by the availability of the parts of the computer required by the next event or operation. Asynchronous transmission – (1) A mode of data communications transmission in which time intervals between transmitted characters may be of unequal length. (2) Transmission independently controlled by start and stop elements at the beginning and end of each character. Synonym: start-stop transmission. Attenuation – Reduction in power level due to line resistance, leakages or induction which results in the received signal being lower in volume than the original transmitted signal. [In optical fiber systems there are other causes of attenuation, such as absorption, scattering and losses into radiation modes. It is usually expressed in decibel (dB).] Audible ringing tone – The information tone sent back to the calling party to indicate the called line is being rung. Audio response unit (ARU) – Output device which provides a spoken response to digital inquiries from a telephone or other device. The response is usually assembled by a computer from a prerecorded vocabulary of words. Authorization code – (1) Code that identifies the customer, and is used for billing purposes and validation by the switch. (2) An identification number that the customer enters when placing a call. Autodial – Automatic dialing; the capability of a terminal, modem, computer or a similar device to place a call and establish a connection over the switched telephone network without operator intervention. Automatic call distributor (ACD) – A switching system designed to queue and/or distribute a large volume of incoming calls to the next available “answering” position among a group of attendants. Automatic callback – A feature of a communications device or network that records, and can dial, the originating phone number of the last incoming call. Automatic dialing unit – A device which automatically generates a predetermined set of dialing digits when the corresponding button is pushed. Automatic message-switching center – In a communications network, location at which messages are automatically directed according to routing information within the message. Automatic number identification (ANI) – The number identifying equipment at local dial offices and sent to message accounting apparatus; the final four numbers of a seven-digit phone number. Automatic route selection (ARS) – Device (or software) which chooses the lowest cost route for long-distance calls over specific lines or services, including WATS, leased, specialized non-Bell common carriers (MCI, Sprint) or direct distance dialing (DDD). Synonym: Least Cost Routing. Auxiliary equipment – Equipment not under direct control of the central processing unit. Synonym: ancillary equipment. Availability – (1) The degree to which a system or resource is operable and not in a state of congestion or failure at any given point in time. (2) The percentage of total trunks in a group which can be accessed by a particular switch.