================================================================================ _ _ _______ | \/ | / _____/ |_||_|etal / /hop __________/ / /___________/ The Dark Tower Phase II <314> 432-0756 Proudly Presents The MCI Telecommunications Glossary Part I Volume III (O - S) Typed and edited by Knight Lightning ================================================================================ - O - OFFERED TRAFFIC The number of call attempts in any specified period of time. OFF HOOK The condition which which results when a telephone handset is lifted from its mounting, allowing the hookswitch to operate. OFF NETWORK ACCESS LINE (ONAL) A connection from a private switched service or transmission network accessing the public switched network. OFF NETWORK CALLING Telephone calls through a private switching system and transmission network which extend to the public telephone system. OFF PREMISES EXTENSION (OPX) An extension telephone or keyset that is geographically separated from its associated PBX. ON HOOK The condition which results when a telephone handset is placed on its mounting, which causes the hook-switch to open up its contacts. ON NETWORK CALLING A term used to describe a call that originates and terminates on private network. OPERATOR ASSISTED CALLS Non-DDD calls requiring manual intervention. ORIGINATING OFFICE The central office that serves the calling party. OTHER COMMON CARRIER (OCC) A company which provides long distance telephone services, other than AT&T. OUT-OF-BAND Any frequency outside the band used for voice frequencies. OUT-OF-BAND SIGNALING Use of a narrow band filters to place the voice signal on a carrier channel below 3,400 CPS, reserving the 3,400 - 3,700 CPS band for supervisory signals. OVERBUILD Adding radio capacity to a telecommunications network. OVERFLOW Switching equipment which operates when the traffic load exceeds the capacity of the regular equipment. - P - PAD A non-adjustable resistance network used to insert transmission loss into a circuit. PHASE JITTER (See JITTER.) POINT-TO-POINT A communications circuit between two terminations which does not connect with a public telephone system. POLLING A progress by which a computer interrogates the "readiness to transmit" status outlying terminals. PORT (See COMPUTER PORT.) POSTAL TELEPHONE AND TELEGRAPH (PTT) Foreign government agencies responsible for regulating communications. PRIMARY AREA A customer"s local telephone calling area. PRIMARY ROUTING POINT The switch designated as the control point for a longhaul telephone call. PRIVATE AUTOMATIC BRANCH EXCHANGE/ A switching system that provides internal PRIVATE BRANCH EXCHANGE (PABX/PBX) telephone communications between stations located on a customer's premises as well as between these stations and public or private telephone networks. PRIVATE LINE A dedicated communications path for use between specific points. PRIVATE LINE SERVICE Subscribers have dedicated, usually full-time communications facilities. Services can range from standard communications lines to highly sophisticated unique arrangements tailored to a customer need. Channels may be established between two points, (e.g., tie together several customer PABX's linking various locations.) Subscribers may elect to purchase transmission facilities and create their own privately owned network. PRIVATE USE NETWORK Two or more private line channels contracted for by a customer and restricted for use by the customer only. PROGRAMMABLE READ ONLY MEMORY (PROM) Memory which is electrically programmed by the equipment manufacturer into a computer and can only be changed with special equipment which erases the previous program. Unaffected by power loss. PROGRAMMED SPEED DIALING Synonym: Abbreviated Dialing. PUBLIC SWITCHED NETWORK (PSN) The nationwide network maintained by AT&T and the independent telephone companies which provide nationwide, unrestricted telephone service. PUBLIC UTILITY COMMISION (PUC)/ The state commisions regulating PUBLIC SERVICE COMMISION (PSC) intrastate communications. PULSE CODE MODULATION (PCM) The conversation of an analog signal to a digital one through rapid sampling of the signal amplitude (minimum 7,000 samples per second). Provides undistorted transmission, even in the presence of noise. PULSE-LINK REPEATER Connects one E&M signaling circuit directly to another. PUSH BUTTON DIALING Synonym: Dual Tone Multi-Frequency. - Q - QUEUE A temporary delay in providing service caused by the inability of the system provided to handle the number of messages or calls attempted. - R - RADIO COMMON CARRIER (RCC) A communications common carrier that provides radio paging and mobile telephone services to the public. RANDAM ACCESS MEMORY (RAM) That portion of a computer's memory which can be accessed non-sequentially and, therefore, is considered the "working memory." RATE CENTER A specified geographic location used by the telephone company to determine interchange mileage for rate.determina- tion purposes. READ ONLY MEMORY (ROM) That portion of a computer's memory which is programmed electrically by the manufacturer, is unchangeable, and is unaffected by a power loss. REDUNDANCY Duplicate equipment that is provided to minimize the effect of failures or equipment breakdowns. REGENERATION The process of recieving distorted signal pulses and from them recreating new pulses at the correct repitition rate, pulse amplitude, and pulse width. REGIONAL OPERATING COMPANY (ROC) There are currently 7 ROC's which own 22 BOC's. RE-HOMING A major network change which involves moving customer services from one switching center to another and establishing the necessary trunking facilities to do so. REMOTE ACCESS The ability of transmission points to gain access to a computer which is at a different location. REPEATER An electronic device used to amplify signals which have become too weak. REPEATING COIL The telephone industry's term for a voice-frequency transformer. RESELLER A business which buys services from one business at a bulk rate and sells portions of those services to multiple users. RESTORATION The re-establishment of service by rerouting, substitution of component parts, or as otherwise determined. RETARD COIL A coil having a large inductance which retards sudden changes of the current flowing through its winding. RINGBACK TONE Synonym: Audible Ringing Tone. RINGDOWN A circuit or a method of signaling where the incoming signal is actuated by alternating current over the circuit. ROTARY DIAL A rotary mechanism having a ten-hole finger wheel which when wound up and released causes pulsing contacts to interrupt the line current and operate the central office selecting equipment in accordance with the digit dialed. ROUTE GUIDE A map showing how a customer's calls are routed. ROUTE OPTIMIZATION Synonym: Least Cost Routing. ROTARY HUNT An arrangement which allows calls placed to seek out an ideal circuit in a pre- arranged multi-circuit group and find the next open line to establish a through circuit. - S - SATELLITE COMMUNICATIONS A vehicle in geosynchronous orbit with the Earth which contains a source of energy, such as solar cells, and amplifies the signals it recieves before transmitting it back to Earth. SECONDARY CARRIER Customer can override their primary carrier selection on a call by call basis and select other IC's to carry their long distance traffic in equal access areas. SELECTIVE CALLING The ability of a transmitting station to specify by the use of assigned codes which of several stations is to receive a message. SERVICE A group of circuits which terminate at the same location and provide the same capabilities. SERVICE AND EQUIPMENT RECORD A list of equipment billed to customer by type, quantity, monthly charge, location, and billing dates. SF SIGNALING (SINGLE-FREQUENCY) A signaling system which uses a 2,600 Hz in-band signal on the voice path. The tone is on in the idle condition, pulsed for dialing, and off when the circuits is in use. SHORT HAUL Curcuits designated for use over distances of 10 - 200 miles. SIGNALING A procedure for indicating to the receiving end of a communications circuit that data is to be transmitted SIGNALING CONVERTER A device with input and output signals that contain the same information but employ different electrical systems for transmitting that information. Used at the terminal of a trunk to convert the equipment signals to the system used on the trunk. Examples are: (1) ring down to SF, (b) E&M to SF. SIGNALING, IN-BAND A type of signaling using an AC signal (usually a 2,600 Hz) within the normal voice band. This signal can be trans- mitted from and end to end of a long voice circuit without any intermediate signaling equipment. Since the signaling is audibile, the signaling equipment must be arranged for "tone on when idle" operation. SIMPLEX (SX) SIGNALING A signaling path over a dry talking circuit which uses the two sides of the circuit in parallel, derived by connecting the midpoints of repeating coils or retardation coils which are across the circuit. SINGLE SIDEBAND RADIO (SSB) A form of amplitude modulation of a radio signal in which only one of the two sidebands is transmitted. Either of the two sidebands may be transmitted, and the carrier may be transmitted, reduced or suppressed. SINGING A continued whistle or howl in an amplified telephone circuit. It occurs when the sum of the repeater gain exceeds the sum of the circuit losses. SOFTWARE (1) Any of the routines, programs, and instructions required to use computers. (2) A written statement of the procedures to be used and the format of the data at every step. SPECIAL GRADE NETWORK TRUNK A trunk specially conditioned by providing amplitudeand delay equalization for the purpose of handling special services such as medium-speed data (600 to 2400 BPS). SPECIALIZED COMMON CARRIER A new type of common carrier specializing in providing transmission facilities. (e.g., Microwave Communication Inc.(MCI), Southern Pacific Communication Co.(SPC), and the satelite communication companies like Satellite Business System (SBS).) SPEED NUMBER A one, three, or four digit number that replaces a seven or ten digit telephone X ] number. These numbers are programmed  --------------------------------------- Select (G/S/T/?/H/*/1-20, Last=9) :