The Hacker's Encyclopedia 1998

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=============================================================================== _ _ _______ | \/ | / _____/ |_||_|etal / /hop __________/ / /___________/ (314)432-0756 Proudly Presents The MCI Telecommunications Glossary Part I Volume II (E - N) Typed and Edited by Knight Lightning =============================================================================== - E - ECHO A signal that has been reflected or otherwise returned with sufficient magnitude and delay to be percieved by the speaker. ECHO RETURN LOSS (ERL) The loss which must be in the echo path to reduce echo to a tolerable amount. ECHO SUPRESSOR A device which detects speech signals transmitted in either direction on a four-way circuit, and introduces loss in the direction of transmission. EIGHT HUNDRED SERVICE (800) A commonly used reference for inward WATS service (See WATS, Inward). EITHER END HOP OFF (EEHO) Uses either Head Hop Off or Tail End Hop Off. ELECTRONIC DATA PROCESSING The use of electronic memories to store, up-date, read, and use information. ELECTRONIC KEY TELEPHONE SETS (EKTS) A generic term indicating key telephones with special buttons which are electronically programmed to access various PBX features. ELECTRONIC SWITCHING SYSTEM (ESS) A Bell System term for electronic ELECTRONICALLY PROGRAMMABLE READ Memory which is initially programmed by ONLY MEMORY (EPROM) the manufacturer. Changes can be made to conform to the customer requirements at their premises. ELECTRONIC TANDEM NETWORK (ETN) 1. A private network automatically and electronically connecting the calling office to the called office through Tandem-Tie-Trunks. The network switches also function as PBX's. 2. An AT&T product name. 3. Used as a generic term a PBX base network. END OFFICE CONVERSATION When an end office offers equal access. ENHANCED PRIVATE SWITCHED A private network utilizing Bell provided COMMUNICATIONS SERVICE (EPSCS) equipment located in the central office and dedicated to a specific customer. E&M LEADS A pair of leads which carry signals between trunk equipment and seperate signaling equipment unit. The M lead transmits battery or ground signals to the signaling equipment, and the E lead recieves open or ground signals from the signaling equipment. E&M SIGNALING An arrangement whereby signaling between a trunk circuit and an associated signaling unit is effected over two leads providing full-time, 2-way, 2-level supervision. ENTERPRISE NUMBER A unique telephone exchange number that permits the called party to be automatically for the incoming calls. Synonym: "Toll Free Number;" INWARD WATS. EQUALIZATION The procedure of compensating for fluctuation in circuit amplitude, delay, or distortion. ERLANG A unit of traffic intensity. One Erlang is the intensity at which one traffic path would be countinuously occupied, e.g., one call per hour. ERLANG B TABLE A method for determining grade of service for a specified amount of traffic. ERROR RATE The probability of an error ocurring during the transmission of a message. EXCHANGE A telephone switching center. EXCHANGE AREA A geographical unit established within a telephone company's serving area for the adminastration of telephone service provided. One schedule of charges applies to the whole area. Usually served by one or more central offices and their associated outside plant. EXCAHNGE NETWORK FACILITIES FOR AT&T's pricing arrangement for local INTERSTATE ACCESS (ENFIA) loops offered to OCCs for connecting the OCC's network to the local telephone company's central office. EXPECTED MEASURED LOSS (EML) The calculated 1 kH loss of the trunk shown on the circuit or design layout record. EXTENDED AREA SERVICE (EAS) A telco tariff giving customers the option whereby the subscriber can pay a higher flat rate in order to obtain geographic coverage without additional per-call charges (non-toll charges). - F - FACILITY Synonym: Circuit. FACSMILE The transmission of pictures, maps or other documents via communications circuits using a device which scans the original document, transforms the image into coded signals and repoduces the original document at a distant point. FEDERAL COMMUNICATIONS COMMISON (FC) The government agency established by the Communications Act of 1934 which regulates the interstate communications industry. FIBER OPTICS High speed transmisson using light to send images ( in telecommunications: voice or data ) through a flexible bundle of glass fibers. FOREIGN EXCHANGE LINES (FX) A special access hardwire circuit that provides service between a telephone at a customer's location and a distant central office. FOUR WIRE CIRCUIT A communications path which employs two separates electrical paths one recieving and one transmitting. FREQUENCY The number of complete cycles per unit of time. FREQUENCY DIVISION MULTIPLEXING (FD) The division of an available frequency into bands. This modulation technique requires the derived channels, each to have their own baseband and that "guardbands" be provided between channels to minimize interference or crosstalk from adjacent channels. FREQUENCY RESPONSE The reaction of frequencies to the circuit components. FULL DUPLEX A circuit which allows transmission of a message in both directions at the same time. FULL PERIOD The condition of a switching system where each input a switching stage has access to every output from the stage. - G - GRADE OF SERVICE The probability of a call being blocked by busy trunks, expressed as a decimal fraction, and usually meaning the busy-hour probability. GROUP 12 circuits processed as a unit in a carrier system. - H - HALF DUPLEX A circuit for transmitting or receiving signals in one direction at a time. HANDSET That portion of the telephone containing hand-held when the telephone is in use. HARDWARE Physical equipment or components of a computer system rather than a programmed method use. HARDWIRE To wire or cable directly between units of equipment. HARMONIC The full multiple of a base frequency. HARMONIC DISTORTION The ratio, expressed in decibels, of the power at the fundamental frequency, to the power of a harmonic of that fundamental. HEAD END HOP OFF (HEHO) A method of traffic engineering whereby calls are completed by using long distance facilities directly off the switch that serves that location. HERTZ (Hz) International standard unit of frequency. Replaces, and is identical to, the order unit "Cycles-per-second." HOMING Returning to the starting position, as in a rotary stepping switch. HOOKSWITCH The device on which the telephone receiver hangs or on which a telephone handset hangs or rests when not in use. The weight of the reciever or handset operates a switch which opens the telephone circuit, leaving only the bell connected to the line. HOT-CUT Virtually instantaneous replacement of one line with another. HYBRID An electronic circuit which performs the wire conversations necessary for the connection of a local loop with a long-haul facility. - I - INTERCEPT To stop a telephone call directed to an improper telephone number, and redirect that call to an operator or a recording. INTERCONNECT 1) The arrangement that permits the connection of customer's telecommunica- tions equipment to a communications common carrier network. 2) The industry name for manufacturers, excluding the Bell system, which provide CPE telephone equipment. INTER-EXCHANGE MILEAGE (IXC) The airline mileage between two cities. Synonym: Long Haul Mileage. INTEREXCHANGE PLANT The facilities between the subscriber switching center and another switching center. INTERFACE The junction or point of interconnection between two systems or equipment having different characteristics. INTERFERENCE Any unwanted noise or crosstalk on a communications circuit which acts to reduce the intelligibilty of the desired signal or speech. INTER-MACHINE TRUNK (IMT) A circuit which connects two automatic switching centers. INTER-OFFICE TRUNK (IOT) A direct trunk between local exchange offices. INTERNATIONAL RECORD CARRIER (IRC) Companies that handle the intra-U.S. portion of international record transmission. INTERSTATE Any connection made between two states. INTRASTATE Anyconnection made that remains within the boundaries of a single state. - J - JACK A connecting device having springs which make electrical contact with mating contacts of a plug. JITTER Short term instability of the amplitude and/or phase of a signal. Commonly called: PHASE JITTER. - K - KEYSET Muti-push button keys located on a telephone which may be punched in sequence for sending telephone number desired, precedence, or routing signals. KEY SYSTEM The equipment utilized to provide the features associated with key sets. - L - LEASED LINES Any circuit or combination of circuits designated to be at the exclusive disposal of a given subscriber. Synonym: Private Line. LEAST COST ROUTING (LCR) A method of automatically selecting the least costly facility for transmission of a call. Synonym: Most Economical Route Selection (MERS): Route Optimization. LEVEL An expression of the relative signal strength at a point in a communications circuit compared to a standard. LOADING A system for adding regularly spaced inductance units to a circuit to improve its transmission characteristics. LOCAL ACCESS AND TRANSPORT AREA Defines the local calling area as (LATA) established by the court ordered AT&T divestiture plan. LOCAL AREA NETWORK (LAN) Intraoffice communication system usually used to provide data transmission in addition to voice transmission. LOCAL LOOP The local connection between the end user and the Class 5 central office. LONG HAUL Circuits spanning considerable distances. LOOP BACK A method of performing transmission tests on a circuit not requiring the assistance of personnel at the distant end. use the metallic loop formed by the trunk conductors and the terminating equipment bridges. - M - MAIN DISTRIBUTION FRAME (MDF) The point where outside plant cables terminate and from which they cross connect to terminal or central office line equipment. MAIN PBX A PBX directly connected to a switch via an access trunk group. MANUAL TIE LINE A tie line which requires the assistance of an attendant at both ends of the circuit in order to complete a call. MASTER GROUP (MG) 240 circuits processed as a unit in a carrier service. MESSAGE TELEPHONE SERVICE (MTS) AT&T's tariffed pricing name for long distance telephone calls. MESSAGE UNIT (MU) A local toll rate calling plan which is time and distance sensitive. METAL OXIDE SEMICONDUCTOR (MOS) A type of computer memory utilizing 1/4 inch square slices of silicon. These silicon slices require constant electric current for the data to be retained. MICROWAVE (M/W) Radio transmission using very short lengths , corresponding to a frequency of 1,000 megahertz or greater. Synonym: Microwave Radio. MICROWAVE RADIO Synonym: Microwave. MODEM A device which modulates and demodulates signals on a carrier frequency and allows the interface of digital terminals with analog carrier systems. MODULATION Alterations in the characteristics of carrier waves. Usually impressed on the amplitude and/or the frequency. MONITORING DEVICE Records data on calls placed through a length of calls, calling location. MOST ECONOMICAL ROUTE SELECTION Synonym: Least Cost Routing (MERS) MULTIPLEXING The act of combining a number of individual message circuits for transmission over a common path. Two methods are used: (1) frequency division, and (2) time division. - N - NETWORK A collection of switches connected to one another by transmission facilities. NETWORK NUMBERING EXCHANGE (NNX) The three digit location code representing the central office. "N" may be any number between "2" and "9" and "X" may be any number. NETWORK TRUNKS Circuits connecting switching centers. NODE A terminal of any branch of a network. NON-BLOCKING A switching network having a sufficient number of paths such that a subscriber originating a call can always reach any other idle subscriber without encountering a busy. NUMBERING PLAN AREA (NPA) A geographical division within which no two telephones will have the same 7 digit number. "N" is any number between "2" and "9"; "P" is always "1" or "0"; and "A" is any number excluding "10." =============================================================================== This concludes Part I Volume II of the MCI Telecommunications Glossary. Look for More G-philes on MCI by Knight Lightning coming soon to Metal Shop! This has been a 2600 Club production Thanx to Taran King