The Hacker's Encyclopedia 1998

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=============================================================================== _ _ _______ | \/ | / _____/ |_||_|etal / /hop __________/ / /___________/ (314)432-0756 Proudly Presents The MCI Telecommunications Glossary Part I Volume I (A - D) taken directly from The MCI School of Telecommunications Management Reference Guide and typed by Knight Lightning =============================================================================== - A - A & B LEADS Designation of leads derived from the midpoints of the two 2-wire pairs comprising a 4-wire circuit. ABBREVIATED DIALING The ability of a telephone user to reach frequently called numbers by using less than seven digits. Synonym: Speed Dialing ACCESS CHARGE A fee paid for the use of local lines. ACCESS CODE A digit or number of digits required to be connected to a privat line arranged for dial access. ACCESS LINE A telephone circuit which connects a customer location to a network switching center. AIRLINE MILEAGE Calculated point-to-point mileage between terminal facilities. ALL TRUNKS BUSY (ATB) A single tone interrupted at a 120 ipm (impulsess per minute) rate to indicate all lines or trunks in a routing group are busy. ALTERNATE ROUTE A secondary communications path used to reach a destination if the primary path is unavailable. 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) A single transmission facility which can be used for either voice or data. AMERICAN STANDARD CODE FOR An 8 level code developed for the INFORMATION INTERCHANGE (ASCII) interchange of information between data processing and communications systems. ANALOG SIGNAL A signal in the form of a continuous varying physical quantity, e.g., voltage which reflects variations in some quantity, e.g., loudness in the human voice. ANNUNICATOR An audible intercept device that states the condition or restrictions associated with circuits or procedures. ANSWER BACK An electrical and/or visual indication to the calling or sending end that the called or received station is on the line. ANSWER SUPERVISION An off-hook signal transmitted toward the calling end of a switched connection when the called party answers. AREA CODE Synonym: Numbering Plan Area (NPA). A three digit number identifying more than 150 geographic areas of the United States and Canada which permits direct distance dialing on the telephone system. A similar global numbering plan has been established for international subscriber dialing. ATTENDANT POSITION A telephone switchboard operator's position. It provides either automatic (cordless) or manual (plug and jack) operator controls for incoming and/or outgoing telephone calls. ATTENTUATION A general term used to denote the decrease in power between that transmitted and that received due to loss through equipment, lines, or other transmission devices. It is usually expressed as a ration in db (decibel). AUDIBLE RINGING TONE An audible signal heard by the calling party during the ringing-interval. AUTHORIZATION CODE An identification number that the caller enters when placing a call which is used for billing purposes. AUTHORIZED USER A person, firm, organization, corporation or any other entity authorized by the customer to send or receive communications over a specific communications network. AUTO ANSWER A machine feature that allows a transmission control unit or station to automatically respond to a call that it receives. AUTOMATIC CALL DISTRIBUTOR (ACD) A switching system designed to queue and/or distribute a large volume of incoming calls to a group of attendents to the next available "answering" position. AUTOMATIC DIALING UNIT A device which automatically generates a predetermined set of dialing digits. AUTOMATIC IDENTIFICATION OF A computer generated report showing all OUTWARD DIALING (AIOD) long distance calls placed over AT&T's toll network. AUTOMATIC NUMBER IDENTIFICATION (ANI) Automatic equipment at a local dial office used on customer dialed calls to identify the calling-station. AUTOMATIC ROUTE SELECTION (ARS) Least cost routing via AT&T CENTREX system. - B - BAND (1) The range of frequencies between two defined limits. (2) In reference to WATS, one of the five specific geographic areas as defined by AT&T. Synonym: BANDWIDTH. BANDWIDTH See BAND. BASEBAND The total frequency band occupied by the aggregate of all the voice and data signals used to modulate a radio carrier. BAUD A unit of signaling speed. The speed in baud is the number of discrete conditions conditions or signal elements per second. If each signal event represents only one bit condition, then Baud is the same as bits per second. When each signal event represents other than one bit, Baud does not equal bits per second. BELL OPERATING COMPANY (BOC) /BELL Any of the 24 AT&T affiliated SYSTEMS OPERATING COMPANY (BSOC) companies providing local service. BELL SYSTEM The aggregate of AT&T's 24 associated telephone companies, Long Lines, Western Electric, and Bell Labs. BILLING NUMBER The MCI term for the number which identifies a customer on a billing location level, assigned to Network Service Customer (by COMS). Assigned for each unique customer name and billing location. For internal use only. BINARY A number system that uses only two characters ("0" and "1"). BIT A binary digit. The smallest unit of coded information. BITS PER SECOND (BPS) The rate at which data transmission is measured. BLOCKED CALLS Attempted calls that are not connected because (1) all lines to the central offices are in use; or (2) all connecting connecting paths through the PBX/switch are in use. BLOCKED ANI ANI prohibited from completing a call over the MCI network. BREAK A means of interrupting transmission, a momentary interruption of a circuit. BROADBAND A transmission facility having a bandwidth of greater then 20 kHz. BUS A heavy conductor, or group of conductors, to which several units of the same type of equipment may be connected. BUSY The condition in which facilities over which a call is to be connected are already in use. BUSY HOUR The time of day when phone lines are most in demand. BUSY TONE A single that is interrupted at 60 ipm (impulses per minute) rate to indicate that the terminal point of a call is already in use. BYTE A group of binary digits that are processed by a computer as a unit. - C - CARRIER High frequency current that can be modulated with voice or digital signals for bulk transmission via cable or radio circuits. CARRIER SYSTEM A system for providing several communications channels over a single path. CATHODE RAY TUBE (CRT) The "television-like" screen used to display the output from a computer. CELLULAR MOBILE RADIO A system providing exchange telephone service to a station located in an auto or other mobile vehicle, using radio circuits to a base radio station which covers a specific geographical area and as the vehicle moves from one area to another, different base radio stations handle the call. CENTRAL OFFICE (CO) A telephone switching center that provides local access to the public network. Sometimes referred to as: Class 5 office, end office, or Local Dial Office. CENTREX, CO PBX Service provided by a switch located at the telephone company central office. CENTREX, CU A variation on Centrex CO provided by a telephone company maintained "Central Office" type switch located at the customer's premises. CENTRAL PRCESSING UNIT (CPU) The control unit within a computer which handles all the intelligent functions of the systems. In a telephone switch, directs all potions of the system to carry out their appropiate functions. Synonym: Common Control. CHANNEL A communication path via a carrier or microwave radio. CHARACTER Any letter, digit, or special symbol. In data transmission would be represented by a specific code made up of a group of binary digits. CIRCUIT A path for the transmission of electromagnetic signals to include all conditioning and signaling equipment. Synonym: Facility CIRCUIT SWITCHING A switching system that completes a dedicated transmission path from sender to receiver at the time of transmission. CLASS OF SERVICE/CLASS MARK (COS) A subgrouping of telephone customers or users for the sake of rate distinction or limitation of service. COAXIAL CABLE A cable having several coaxial lines under a single protective sheath. Usually used as a high capicity carrier in urban areas between interexchange and toll offices. CODEC Coder-Decoder. Used to convert analog signals to digital form for transmission over a digital median and back again to the original analog form. COMMON CARRIER A government regulated private company that provides the general public with telecommunications services and facilities. COMMON CHANNEL INTEROFFICE A digital technology used by AT&T to SIGNALING (CCIS) enhance their Integrated Services Digital Network. It uses a seperate data line to route interoffice signals to provide faster call set-up and more efficient use of trunks. COMMON CONTROL SWITCHING ARRANGEMENT An arrangement for telecommunications (CCSA) networks in which common controlled switching machines are used to route traffic over network routes and access lines. The switching machine may be shared with other users and is maintained by the telephone company. COMPUTER PORT/TKI PORT The interface through which the computer connects to the communications circuit. CONDITIONING EQUIPMENT Equipment modifications or adjustments necessary to match transmission levels and impedances and which equalizes transmission and delay to bring circuit losses, levels, and distortion within established standards. CONFIGURATION The combination of long-distance services and/or equipment that make up a communications system. CONTROL UNIT (CU) The central processor of a telephone switching device. CORPORATE ID NUMBER The MCI term for the number which identifies a customer on a corporate level. (Not all MCI customers have this). COST COMPONENT The price of each type of long distance service and/or equipment that constitutes a configuration. COST PER HOUR (CPH) Total cost of different services divided by total holding time (in minutes). CROSS CONNECTION The wire connections running between terminals on the two sides of a distribution frame, or between binding posts in a terminal. CROSS TALK The unwanted energy (speech or tone) transferred from one circuit to another circuit. CUSTOMER OWNED AND MAINTAINED (COAM) Customer provided communications apparatus, and their associated wiring. CUSTOMER PREMISE EQUIPMENT (CPE) Telephone equipment, usually including wiring located within the customer's part of a building. CUT To transfer a sevice from one facility to another. CUT THROUGH The establishment of a complete path for signaling and/or audio communications. - D - DATA Any representation, such as characters to which a meaning is assigned. DATA COMMUNICATIONS The movement of coded information by means of electronic transmission systems. DATA SET A device which converts data into signals suitable for transmission over communications lines. DATA TERMINAL A station in a system capable of sending and/or receiving data signals. DECIBEL (db) A unit measurment represented as a ratio of two voltages, currents or powers and is used to measure transmission loss or gain. DELAY DIAL A dialing configuration whereby local dial equipment will wait until it receives the entire telephone number before seizing a circuit to transmit the call. DELTA MODULATION (DM) A variant of pulse code modulation whereby a code representing the difference between the amplitude of a sample and t~he amplitude of a previous one is sent. Operates well in the presence of noise, but requires a wide frequency band. DEMODULATION The process of retrieving data from a modulated signal. DIAL LEVEL The selection of stations or services associated with a PBX using a one to four digit code (e.g., dialing 9 for access to outside dial tone). DIAL PULSING The transmitting of telephone address signals by momentarily opening a DC circuit a number of times corresponding to the decimal digit which is dialed. DIAL REPEATING TIE LINE/ A tie line which permits direct station DIAL REPEATING TIE TRUNK to station calling without use of the attendant. DIAL SELECTIVE SIGNALING A multipoint network in which the called party is selected by a prearranged dialing code. DIAL TONE A tone indicating that automatic switching equipment is ready to receive dial signals. DIALING PLAN A description of the dialing arrangements for customer use on a networks. DIGITAL Referring to the use of digits to formulate and solve problems, or to encode information. DIMENSION CUSTOM TELEPHONE SERVICE AT&T's electronically programmable (DCTS) telephone station sets which use special buttons to access PBX features. DIRECT DISTANCE DIALING (DDD) A toll service that permits customers to dial their own long distance call without the aid of an operator. DIRECT INWARD DIALING (DID) A PBX or CENTREX feature that allows a customer outside the system to directly dial a station within the system. DIRECT OUTWARD DIALING A PBX or CENTREX feature that allows a station user to gain direct access to an exchange network. DROP That direction of a circuit which looks towards the local operator. DRY CIRCUIT A circuit which transmits voice signals and carries no direct current. DUAL TONE MULTI-FREQUENCY (DTMF) Also know as Touch Tone. A type of signaling which emits two distinct frequencies for each indicaated digit. DUPLEX Simultaneous two-way independent transmission. DX SIGNALING A long-range bidirectional signaling method using paths derived from transmission cable pairs. It is based on a balanced and symetrical circuit that is identical at both ends. This circuit presents an E&M lead interface to connecting circuits. =============================================================================== This concludes Part 1 Volume I of the MCI Telecommunications Glossary. Look for more G-philes from The MCI School of Telecommunications Management Reference Guide coming soon. This has been a 2600 Club production Thanx to Taran King