 Cellular Telecommunications Industry Association. ventional dial-up long distance calls placed over a (USA trade association.) telephone network without operator assistance.) Common Technical Regulation. (European Com- Digital Distribution Frame. (Frame for physical con- munity mandatory standard.) nection of transmission lines. See also ADDF and Conformance Test Services. (Part of European Com- MDDF.) mission initiative.) Direct Dialling In. (External caller able to dial di- Clear To Send. (Control code used for data trans- rectly to an extension.) mission in modems.) Distributed Data Interface. (Proposal to run the Continuous Variable Slope Delta modulation. (Pro- FDDI standard over unshielded twisted pair.) prietary method used for speech compression. Also Digital Data Network. called CVSDM.) Defence Data Network. (US military network, Continuous Wave. derived from the ARPANET.) Distributed Data Processing. Digital Data Service. (North American data service.) Demand Assigned Multiple Access. Defect Events. (E.g. loss of signal, loss of frame DAMPS Digital Advanced Mobile Phone System. (Digital synchronisation, etc. CCITT M.550 for digital cir- version of AMPS, which has the same basic archi- cuit testing.) tecture and signalling protocol.) Acronyms 62/7 Digital European Cordless Telephony. (Or Digital Digital Signal level 0. (Part of the US transmission European Cordless Telecommunications. ETSI hierarchy, transmitting at 64kbit/s. DS-1 transmits at standard, intended to be a replacement for CT2.) 1.544Mbit/s, DS-2 at 6.312Mbit/s, etc.) Dolby Enhanced Delta Modulation. Destination Service Access Point. (Refers to the DELTA Developing European Learning through Techno- address of service at destination.) logical Advance. (European Community informa- Double Sideband. tion technology and telecommunication programme DSBEC Double Sideband Emitted Carrier. associated with training.) DSBSC Double Sideband Suppressed Carrier modulation. DEPSK Differentially Encoded Phase Shift Keying. (A method for amplitude modulatio