Find allmost all Acronyms & Abbreviations used in Telecom & IT sectors.
| A | |
| A3 | GSM Authentication Algorithm |
| A5 | GSM Stream Cipher Algorithm |
| A8 | SM Cipher Key Generating Algorithm (GSM) |
| AA | Auto Answer |
| AAA | Authentication, Authorisation, Accounting |
| AAL | ATM Adaptation Layer |
| AAR | Automatic Alternate Routing |
| AARP | AppleTalk Address Resolution Protocol |
| AARTS | Automatic Audio Remote Test Set |
| AAV | Alternate Access Vendors |
| AB | Answer Back |
| ABC | Advanced Broadband Communications |
| A-bis | BSC-BTS Interface |
| ABM | Asynchronous Balanced Mode (HDLC) |
| ABR | Available Bit Rate (ATM) |
| ABR | Area Border Router |
| ABS | Alternate Billing Service |
| AC | Access Charge |
| AC | Area Code |
| AC | Authorisation Code |
| AC | Access Control (Token Ring FDDI) |
| AC | Authentication Centre |
| ACA | Australian Communications Authority |
| ACA | Automatic Circuit Assurance |
| ACC | Automatic Callback Calling |
| ACCH | Associated Control Channel |
| ACD | Automatic Call Distribution |
| ACDS | Automatic Call Distribution Systems |
| ACE | Authentication Encryption |
| ACE | Advanced Communications Experiments |
| ACEK | Authentication Encryption Key |
| ACF | Advanced Communication Function |
| ACITS | Advisory Committee on Information Technology Standardisation (SOG-IT) |
| ACK | Acknowledgement |
| ACNA | Access Carrier Name Abbreviation |
| ACP | Access Control Point |
| ACQ | All Call Query (number portability) |
| ACR | Allowed Cell Rate |
| ACRE | Authorisation and Call Routing Equipment |
| ACS | Asynchronous Communications Server |
| ACSE | Association Control Service Element |
| ACTE | Approvals Committee for Terminal Equipment |
| ACTOM | Advisory Committee on Technical and Operational Matters (of Inmarsat) |
| ACTS | Advanced Communications Technology Satellite |
| ACTS | Advanced Communications Technologies and Services |
| ACU | Automatic Calling Unit |
| AD | Abbreviated Dialling |
| A-D | Analogue-to-Digital |
| ADC | Analogue-to-Digital Converter |
| ADC | Access Deficit Charge or Contribution |
| ADC | Analogue-to-Digital Conversion |
| ADCCP | Advanced Data Communications Control Procedures |
| ADCT | Adaptive Discrete Cosine Transform Coding (video coding) |
| ADH | Automatic Data Handling |
| ADIF | Analogue Digital Interface |
| ADM | Add Drop Multiplexer |
| ADP | Automatic Data Processing |
| ADPCM | Adaptive Differential Pulse Code Modulation |
| ADPE | Automatic Data Processing Equipment |
| ADPSSO | Automatic Data Processing System Security Officer |
| ADS | Asynchronous Data Switching |
| ADSL | Asymmetric Digital Subscriber Line |
| ADU | Automatic Dialling Unit |
| ADX | Automatic Data Exchange |
| AECMA | Association Européenne des Constructeurs de Matériel Aerospatial (European Association for the Construction of Aero-Space Equipment) |
| AECN | Alternate Exchange Carrier Name (US) |
| AENOR | Associación Espanola de Normalización (Standards Association Spain) |
| AEROM | Electrically Alterable Read Only Memory |
| AF | Audio Frequency |
| AFC | Area Frequency Coordinator |
| AFC | Automatic Frequency Control |
| AFE | Analogue Front End |
| AFIPS | American Federation of Information Processing Societies |
| AFMS | Administrative Frequency Management System |
| AFNOR | Association Française de Normalisation (Standards Association France) |
| AFUTT | Association Française des Utilisateurs du Téléphone et des Télécommunications (French Telegraphs and Telephone Users’ Association) |
| AGC | Automatic Gain Control |
| AGCH | Access Grant Channel |
| AGCOM | Autorità per le Garanzie nelle Comunicazioni (Italy) |
| AGE | Aerospace Ground Equipment |
| AGRAS | Air-Ground Radiotelephone Automated Service |
| AH | Authentication Header (IPSec security protocol) |
| AI | Artificial Intelligence |
| AIM | Amplitude Intensity Modulation |
| AIM | Ascend Inverse Multiplexing |
| AIM | Advanced Informatics for Medicine (Application Programme of DG XIII/F) |
| AIN | Advanced Intelligent Network |
| AIO | Asynchronous Input/Output |
| AIOD | Automatic Identification of Outward Dialling |
| AIP | Application Infrastructure Provider |
| AIP | Advanced Information Processing |
| AIP | Advanced Infrastructure Planning |
| AIS | Automated Information System |
| AIS | Alarm Indication Signal |
| AITS | Acknowledged Information Transfer Service (ITU-T) |
| AJ | Anti-Jamming |
| AL | Access Line |
| ALBO | Automatic Line Build Out |
| ALC | Automatic Level Control |
| ALC | Automatic Load Control |
| ALE | Automatic Link Establishment |
| ALE | Approval Liaison Engineer (UK) |
| ALEC | Alternative Local Exchange Carrier (US) |
| ALI | Automatic Location Information |
| ALI | Analogue Line Interface |
| ALU | Arithmetic and Logic Unit |
| AM | Amplitude Modulation |
| AM/PM/VSB | Amplitude Modulation/Phase Modulation/Vestigial Sideband |
| AMA | Automatic Messaging Accounting |
| AMADNS | AMA Data Networking System |
| AMC | Administrative Management Complex |
| AME | Amplitude Modulation Equivalent |
| AME | Automatic Message Exchange |
| AMI | Alternative Mark Inversion |
| AMPS | American Mobile Phone System (analogue cellular) |
| AMPSSO | Automated Message Processing System Security Officer |
| AMR | Adaptive Multi Rate |
| AMTS | Automated Maritime Telecommunications System |
| AN | Annunciator |
| ANACOM | National Communications Authority (Portugal) |
| ANATEL | Agência Nacional de Telecomunicações do Brasil (Brazil) |
| ANC | All Number Calling |
| ANI | Automatic Number Identification (ISDN) |
| ANL | Automatic Noise Limiter |
| ANM | Answer Message |
| ANR | Automatic Network Routing |
| ANRC | National Regulatory Authority of Romania |
| ANRT | Agence Nationale de Réglementation des Telecommunications (Morocco) |
| ANRTI | National Regulatory Agency in Telecommunications and Informatics (Moldova) |
| ANS | American National Standard |
| ANS | Advanced Network Services |
| ANSI | American National Standards Institute |
| ANT | ADSL Network Terminator |
| AOA | Angle of Arrival |
| AOC | All Ones Code |
| AOC | Advice of Charge |
| AOS | Alternative Operator Services |
| AP | Attendant Position |
| AP | Anomalous Propagation |
| AP | Access Point (UPT) |
| AP | Application Pilot |
| APA | Access Provider Architecture |
| APC | Adaptive Predictive Coding |
| APCM | Adaptive Pulse Code Modulation |
| APDU | Application Protocol Data Unit |
| API | Application Programming Interface |
| APK | Amplitude Phase-Shift Keying |
| APL | Analogue Private Line |
| APL | Average Picture Level |
| APLT | Advanced Private Line Termination |
| APNSS | Analogue Private Network Signalling System |
| APON | ATM Passive Optical Network |
| APP | Applications Portability Profile |
| APPC | Advanced Program-to-Program Communications |
| APPN | Advanced Peer-to-Peer Networking |
| APS | Automatic Protection Switching |
| APT | Application Pilot Transfer (Group) |
| APT | Telephony Applications System |
| AR | Alternative Recall |
| AR | Access Rate |
| AR | Alternate Route |
| ARA | Access Registration Point (UPT) |
| ARD | Automatic Ring Down |
| ARDIS | Advanced Radio Data Information Service |
| ARE | Autorité de Régulation (Mauritania) |
| ARESEP | Autoridad Reguladora de los Servicios Públicos (Costa Rica) |
| ARIN | American Registry for Internet Numbers |
| ARINC | Aeronautical Radio Incorporated (Aviation) |
| ARM | Asynchronous Response Mode (HDLC) |
| ARP | Address Resolution Protocol |
| ARPU | Average Revenue Per User |
| ARPT | Autorité de Régulation de la Poste et des Telecommunications (Algeria) |
| ARPTC | Autorité de Régulation de la Poste et des Télécommunications du Congo ( DR Congo) |
| ARQ | Automatic Repeat Request |
| ARS | Automatic Route Selection |
| ARSR | Air Route Surveillance Radar |
| ART | Audible Ringing Tone |
| ART | Autorité de Régulation des Telecommunications (France) |
| ART | Agence de Régulation des Télécommunications (Senegal) |
| ART&P | Autorité de Réglementation des Secteurs de Postes et Télécommunications (Togo) |
| ARTEL | Agence de Régulation des Télécommunications (Gabon) |
| ARTEL | Autorité Nationale de Régulation des Télécommunications (Burkina Faso) |
| ARU | Audio Response Unit |
| ARU | Alarm Relay Unit |
| AS | Analogue Signal |
| AS | Answer Supervision |
| AS | Anti Spooling |
| ASAM | ATM Subscriber Access Multiplexer |
| ASCI | Advanced Speech Cal Items |
| ASCII | American Standard Code for Information Interchange |
| ASCU | Agent-Set Control Unit |
| ASI | ATM Service Interface |
| ASIC | Application-Specific Integrated Circuit |
| ASK | Amplitude Shifting Key |
| ASN | Auxiliary Signal Network |
| ASN | ATM Switching Network |
| ASN.1 | Abstract Syntax Notation 1 (ISO) |
| ASOG | Access Service Ordering Guidelines |
| ASP | Adjunct Service Point |
| ASP | Application Service Provider |
| ASP | Advanced Speech Processor |
| ASR | Airport Surveillance Radar |
| ASR | Automatic Send and Receive |
| ASR | Access Service Request |
| ASR | Automatic Speech Recognition |
| ASR | Answer:Seize Ratio |
| ASTIC | Anti-Sidetone Induction Coil (Circuit) |
| ASVD | Analogue Simultaneous Voice and Data |
| AT | Attentuation |
| AT | Access Tandem |
| AT | Assistive Technology |
| AT | Asynchronous Transfer Mode |
| AT&T | American Telephone and Telegraph Corporation |
| ATB | All Trunks Busy |
| ATC | Adaptive Transform Coding |
| ATCI | Agence des Télécommunications de Côte d’Ivoire |
| ATD | Asynchronous Time Division Switching |
| ATDM | Asynchronous Time Division Multiplexing |
| ATDMA | Advanced Time Division Multiple Access |
| ATE | Automatic Test Equipment |
| ATE | Automatic Telephone Exchange |
| ATH | ATM Transmission Hierarchy |
| ATIS | Alliance for Telecommunications Industry Solutions |
| ATIS | Automatic Transmitter Identification System |
| ATM | Active Traffic Management |
| ATM | Asynchronous Transfer Mode |
| ATM | Automated Teller Machine |
| ATMM | ATM Management Process |
| ATS | ATM Transmission System |
| ATSC | Advanced Television Systems Committee |
| ATU | ADSL Transmission Unit |
| ATU-C | ADSL Transmission Unit, Central |
| ATU-R | ADSL Transmission Unit, Remote |
| ATRP | Telecommunications, Broadcasting and Post Agency (Slovenia) |
| AU | Alternative Use |
| AU | Adaptation Unit |
| AUC | Authentication Centre |
| AUI | Attachment Unit Interface |
| AUP | Acceptable Use Policy |
| AUSM | ATM User Service Module |
| AUTODIN | Automatic Digital Network |
| AUTOSEVO- COM | Automatic Secure Voice Communications Network |
| AUTOVON | Automatic Voice Network |
| AVD | Alternate Voice Data |
| AVI | Audio Video Interleave |
| AVM | ATM Voice Multiplexer |
| AVM | Audio Visual Management |
| AW | Administrative Weight |
| AWG | American Wire Gauge |
| AWGN | Additive White Gaussian Noise |
| AXE | Automatic Cross-Connection Equipment (also known as ACE) |
| B | |
| B2B | Business-to-Business |
| B2C | Business-to-Consumer |
| B3ZS | Binary/Bipolar Three Zero Substitution (line-code) |
| B6ZS | Binary 6-Zero Substitution (line-code) |
| B8ZS | Binary 8-Zero Substitution (line-code) |
| BA | Balanced Asynchronous (HDLC) |
| BA | Basic Access |
| BABT | British Approvals Board for Telecommunications |
| BACP | Bandwidth Allocation Control Protocol (PPP ISDN) |
| BAIC | Barring of All Incoming Calls |
| BALUN | Balanced, Unbalanced Device |
| BAOC | Barring of All Outgoing Calls |
| BAP | Bandwidth Allocation Protocol |
| BBS | Bulletin Board Service |
| BBSK | Binary Phase Shift Keying |
| Bc | Committed Burst |
| BCA | Bhutan Communications Authority |
| BCC | Block Check Character |
| BCCH | Broadcast Control Channel |
| BCD | Binary-Coded Decimal |
| B-CDMA | Broadband Code Division Multiple Access |
| BCF | Budget Cross-Flow Model |
| BCH | Bose-Chaudhuri-Hocquenghem (forward error correction technique) |
| BCI | Bit-Count Integrity |
| BCLB | Broadband Connectionless Bearer Service (ATM) |
| BCOB | Broadband Connection-Oriented Bearer Service (ATM) |
| BCPN | Business Customer Premises Network |
| Bd | Baud |
| BDCS | Broadband Digital Cross-Connect System |
| BDF | Building Distribution Frame |
| BDSL | See VDSL |
| BDT | Telecommunication Development Bureau of the ITU |
| BECN | Backward Explicit Congestion Notification |
| B-ED | Best-Effort Delivery |
| BEMS | Business Exchange Measured Service |
| BEP | Back-End Processor |
| BER | Basic Encoding Rules |
| BER | Bit Error Rate |
| BER(T) | Bit Error Rate (Test) |
| BETRS | Basic Exchange Telecommunications Radio Service |
| BEX | Broadband Exchange |
| BFO | Beat Frequency Oscillator |
| BFWA | Broadband Fixed Wireless Access |
| BH | Busy Hour |
| BHCA | Busy Hour Call Attempts |
| BICC | Bearer Independent Call Control |
| B-ICI | Broadband Intercarrier Interface (ATM) |
| BIH | International Time Bureau |
| BIOS | Basic Input-Output System |
| BIP | Bit Interleaved Parity |
| BIPT | Belgian Institute for Posts and Telecommunications |
| B-ISDN | Broadband Integrated Services Digital Network |
| BIT | Built-In Test |
| BITE | Built-In Test Equipment |
| BIU | Bus Interface Unit |
| B-LE | Broadband Local Exchange (B-ISDN) |
| BLEC | Building Local Exchange Carrier (US) |
| BLER(T) | Block Error Rate (Test) |
| BLOB | Binary Large Object |
| BLSR | Bidirectional Line Switch Ring |
| BNI | Broadband Network Interface |
| BNM | Broadband Network Module |
| BNN | Boundary Network Node |
| BNS | Broadband Network Service |
| BOC | Bell Operating Company (USA) |
| BONDING | Bandwidth On Demand Interoperability Group |
| BOOTP | Bootstrap Protocol |
| BORSCHT | Battery supply, Overvoltage protection, Ringing current, Supervision, Coding, Hybrid conversion, Testing |
| BOT | Build-Operate-Transfer Agreement |
| BP | Band Pass |
| BP | Bypass |
| BP | Breakeven Point |
| BPDU | Bridge Protocol Data Unit |
| BPI | Baseline Privacy Interface |
| BPSK | Binary Phase Shifting Key |
| BPV | Bipolar Violation |
| BPVR | Bipolar Violation Ratio |
| BQB | Bluetooth Qualification Body |
| BQP | Bluetooth Qualification Programme |
| BR | Radiocommunication Bureau |
| BRA | Basic Rate Access |
| BRAS | Broadband Access Server |
| BRC | Block Redundancy Check |
| BRF | Bridge Relay Function |
| BRI | Basic Rate Interface (ISDN) |
| BRITE | Basic Rate Interface Transmission Equipment |
| BRLU | Broadband Remote Line Unit |
| BS | Base Station |
| BS | Bearer Service |
| BS | Bellset |
| BSA | Basic Serving Arrangement |
| BSA | Business Segmented Accounts |
| BSC | Base Station Controller |
| BSC | Binary Synchronous Communication |
| BSE | Basic Service Element |
| BSGL | Branch Systems General Licence (UK) |
| BSI | British Standards Institute |
| BSIC | Base Transceiver Station Identity Code |
| BSP | Bell System Practice (US) |
| BSP | Building Service Provider |
| BSS | Base Station System / Subsystem |
| BSS | Basic Synchronised Subset |
| BSS | Billing Support System |
| BSS | Broadband Switching System |
| BSS | Business Support System |
| BSSMAP | Base Station Systems Management Application Part |
| BT | Busy Tone |
| BT | Block Terminal |
| BT | British Telecommunications PLC |
| BT | Burst Tolerance (ATM) |
| B-TA | Broadband Terminal Adapter (B-ISDN) |
| BTA | Botswana Telecommunications Authority |
| BTAM | Basic Telecommunications Access Method |
| B-TE | Broadband Terminal Equipment (B-ISDN) |
| BTN | Billing Telephone Number |
| BTNR/BTR | British Telecom Network Requirement |
| BTO | Build-Transfer-Operate (see also BOT) |
| BTRC | Bangladesh Telecommunication Regulatory Commission |
| BTS | Base Transceiver Station Terminal |
| BUS | Broadcast and Unknown Server |
| BVI | Bridge Group Virtual Interface |
| BW | Bandwidth |
| BXM | Broadband Switch Module |
| C | |
| C/kT | Carrier-to-Receiver Noise Density |
| C/O | Cut-Off |
| C/S | Client/Server |
| CA | Call Appearance |
| CA | Certification Authority |
| CAA | Civil Aviation Authority (UK) |
| CABS | Carrier Access Billing System |
| CAC | Carrier Access Code |
| CAC | Connection Admission Control (ATM) |
| CACS | Centralised Alarm Control System |
| CAD | Computer Aided Design |
| CAE | Computer-Aided Engineering |
| CAF | Controllable ATM Fabric |
| CAI | Common Air Interface |
| CALC | Customer Access Line Charge |
| CALEA | The Communications Assistance for Law Enforcement Act (US) |
| CAM | Computer Aided Manufacturing |
| CAM | Content Addressable Memory |
| CAMA | Centralised Automatic Message Accounting |
| CAMEL | Customised Applications for Mobile Network Enhanced Logic |
| CAN | Campus Area Network |
| CAN | Competitive Access Network |
| CAN | Cosmopolitan Area Network |
| CAP | CAMEL Application Protocol |
| CAP | Carrierless Amplitude Modulation/Phase Modulation |
| CAP | Competitive Access Provider |
| CAP | Customer Administration Panel |
| CAPEX | Capital Expanditures |
| CAPI | Common ISDN API |
| CAPS | Common ISDN API Service |
| CARS | Cable Antenna Relay Services |
| CAS | Channel Associated Signalling |
| CAS | Centralised Attendant Service |
| CAS | Cordless Access Service |
| CASE | Computer-Aided Software Engineering |
| CASE | Computer Aided System Engineering |
| CASP | Communications Application Service Provider |
| CAT | Carrier Access Tariff |
| CATscan | Computed Axial Tomodensitometry Scanner |
| CATV | Cable Television / Community Antennae Television |
| CAU | Controlled Access Unit (Token Ring) |
| CAVE | Cellular Authentication and Voice Encryption |
| CAZ | Communications Authority of Zambia |
| CB | Cell Broadcast |
| CB | Central Battery |
| CB | Channel Bank |
| CB | Citizens Band |
| CBAC | Context-Based Access Control |
| C-BAT | Cost-Benefit Analysis Toolkit |
| CBDS | Connectionless Broadband Data Service (ETSI) |
| CBI | Cross-Border Interconnect |
| CBR | Constant Bit Rate (ATM) |
| CBRA | Constant Bit-Rate Adapter |
| CBS | Central Battery Signalling |
| CBS | Common Base Station |
| CBX | Computerised Branch Exchange |
| CC | Common Carrier (US) |
| CC | Cost Component |
| CC | Cross-Connect |
| CCA | Carrier-Controlled Approach |
| CCA | Current Cost Accounting |
| CCB | Call Control Block |
| CCB | Coin Collecting Box |
| CCBS | Completion of Calls to Busy Subscribers |
| CCC | Clear Channel Capability |
| CCCH | Common Control Channel |
| CCD | Charge Coupled Device |
| CCF | Call Control Function |
| CCH | Connections per Circuit per Hour |
| CCK | Communications Commission of Kenya |
| CCIR | Comité Consultatif International de Radiodiffusion (International Radiodiffusion Consultative Committee) |
| CCIR | Comité Consultatif International des Radiocommunications (Consultative Committee on International Radiocommunications) |
| CCIS | Common Channel Interoffice Signalling |
| CITC | Communication and Information Technology Commission (Saudi Arabia) |
| CCITT | Comité Consultatif International Télégraphique et Téléphonique (Consultative Committee on International Telegraphy and Telephony) |
| CCL | Continuous Communications Link |
| CCLC | Carrier Common Line Charge |
| CCP | Calling Card Platform |
| CCR | Common Control Redundancy |
| CCR | Customer Controlled Reconfiguration |
| CCS | Call Connect System |
| CCS | Common Channel Signalling |
| CCS | Hundred Call Seconds per Hour |
| CCSA | Common Control Switching Arrangement |
| CCSS6 | Common Channel Signalling System No.6 |
| CCSS7 | Common Channel Signalling System No.7 |
| CCT | Circuit |
| CCTV | Closed-Circuit Television |
| CCU | Common Control Unit |
| CCW | Cable Cutoff Wavelength |
| CD | Call Deflection |
| CD | Carrier Detect |
| CD ROM | Compact Disc Read Only Memory |
| CD | Collision Detection (LAN) |
| CD | Compact Disc |
| CDAA | Circularly Disposed Antenna Arrays |
| CDC | Call Directing Code |
| CDC | Control Data Corporation |
| CDDI | Copper Distributed Data Interface |
| CDF | Channel Definition Format |
| CDF | Combined Distribution Frame |
| CDF | Cumulative Distribution Function |
| CDMA | Code Division Multiple Access |
| CDO | Community Dial Office |
| CDPD | Cellular Digital Packet Data |
| CDPSK | Coherent Differential Phase-Shift Keying |
| CDR | Call Detail Record |
| CDT | Control Data Terminal |
| CDU | Central Display Unit |
| CDV | Cell Delay Variation |
| CDVT | Cell Delay Variation Tolerance |
| C-E | Communications-Electronics |
| CE | Conditioning Equipment |
| CE | Conformité Européenne (European conformity mark) |
| CEB | Comité Electrotechnique Belge (Electrotechnical Committee Belgium) |
| CEC | Commission of the European Communities |
| CEI | Comitato Electrotecnico Italiano (Electrotechnical Committee Italy) |
| CEI | Comparably Efficient Interconnection |
| CEIR | Central Equipment Identity Register |
| CELEX | European Community Legislation Database |
| CELP | Code Excited Linear Prediction Compression |
| CENELEC | Comité Européen de Normalisation Electrotechnique (European Committee for Standardisation and European Committee for Electrotechnical Standardisation) |
| CENTREX | Central Office Exchange (PBX-like Service) |
| CEP | Circular Error Probable |
| CEPT | Conférence Européenne des Postes et Télécommunications (European Conference of Post and Telecommunication Administrations) |
| CER | Cell Error Ratio |
| CERN | Centre Européen pour la Recherche Nucléaire (European Centre for Nuclear Research) |
| CERT | Computer Emergency Response Team |
| CES | Circuit Emulation Service |
| CFA | Carrier Facility Assignment |
| CFB | Call Forward Busy |
| CFE | Contractor-Furnished Equipment |
| CFNR | Call Forward No Reply |
| CFR | Code of Federal Regulations (US) |
| CFRAD | Cisco Frame Relay Access Device |
| CFS | Common Functional Specifications |
| CGI | Common Gateway Interface |
| CGSA | Cellular Geographical Service Area |
| CHAP | Challenge Handshake Authentication Protocol |
| ChR | Channel Reliability |
| CI | Cell Identity |
| CI | Computer Interconnect |
| CIAS | Circuit Inventory and Analysis System |
| CIC | Carrier Identification Code |
| CIC | Content Indicator Code |
| CICS | Customer Information Control System |
| CID | Caller Identification |
| CID | Channel ID |
| CID | Craft Interface Device Terminal |
| CIDR | Classless Inter-Domain Routing |
| CIF | Common Intermediate Format |
| CIFAX | Ciphered Facsimile |
| CIGREF | Club Informatique des Grandes Entreprises Françaises (IT Society for major French companies) |
| CILE | Call Information Logging Equipment |
| CIM | Computer Integrated Manufacturing |
| CiR | Circuit Reliability |
| CIR | Channel Impulse Response |
| CIR | Committed Information Rate |
| CISPR | International Special Committee on Radio Interference |
| CIT | Computer Integrated Telephony |
| CIX | Commercial Internet Exchange |
| CL | Connectionless |
| CLASS | Custom Local Area Signalling Service |
| CLAW | Common Link Access for Workstations |
| CLE | Customer Local Equipment |
| CLEC | Competitive Local Exchange Carrier |
| CLI | Calling Line Identity/Identification |
| CLI | Command Language Interpreter |
| CLI | Command Line Interface |
| CLID | Calling Line Identification (ISDN CLASS) |
| CLIP | Calling Line Identity Presentation |
| CLIR | Calling Line Identification Restriction |
| CLNP | Connectionless Network Protocol (ISO ITU-T) |
| CLNS | Connectionless Network Service (ISO ITU-T) |
| CLP | Cell Loss Priority |
| CLR | Cell Loss Ratio |
| CLS | Call Logging System |
| CLTS | Connectionless-Mode Transport Service |
| CM | Communications Management |
| CM | Configuration Management |
| CMA | Communications Management Association |
| CMA | Construction and Maintenance Agreement |
| CMC | Coherent Multi Channel (optical transmission) |
| CMI | Coded Mark Inversion |
| CMIP | Common Management Information Protocol |
| CMIS | Common Management Information Service |
| CMISE | Common Management Information Service Element (ISO) |
| CMNS | Connection-Mode Network Service |
| CMOS | Complementary Metal Oxide Semiconductors |
| CMR | Cellular Mobile Radio |
| CMRR | Common-Mode Rejection Ratio |
| CMRS | Commercial Mobile Radio Service |
| CMT | Comisión del Mercado de las Telecomunicaciones (Spain) |
| CMT | Connection Management |
| CMTS | Cable Modem Termination System |
| CN | Core Network |
| CNA | Change of Number Announcement |
| CNAE | Customer Network Access Equipment |
| CNAM | Caller Name |
| CNC | Comisión Nacional de Comunicaciones (Argentina) |
| CNCA | Carrier Non-Compatible Applications |
| C-Net | Analogue Cellular System Standard |
| CNI | Calling Number Identification |
| CNI | Change of Number Interception |
| CNM | Customer Network Management |
| CNMS | Customer Network Management System |
| CNR | Carrier-to-Noise Ratio |
| CNS | Complementary Network Service |
| CO | Central Office |
| CO | Call Office |
| CO FRAD | Central Office Frame Relay Access Device |
| COAM | Customer Owned and Maintained Equipment |
| COAX | Coaxial Cable |
| COBOL | Common Business-Oriented Language |
| CoC | Certificate of Conformity |
| CODEC | Coder/Decoder |
| CODIT | Code Division Test Bed |
| COFDM | Coded Orthogonal Frequency Division Multiplex |
| COFETEL | Comisión Federal de Telecomunicaciones (Mexico) |
| CTU | Czech Telecommunication Office |
| COG | Centralised Ordering Group |
| CO-LAN | Central Office-Based Local Area Network |
| COLP | Connected Line Identification Presentation |
| COLR | Connected Line Identification Restriction |
| COMINT | Communications Intelligence |
| COMJAM | Communications Jamming |
| COMPUSEC | Computer Security |
| ComReg | Commission for Communications Regulation (Ireland) |
| Comsat | Communications Satellite Corporation |
| COMSEC | Communications Security |
| CON | Concentrator |
| CONATEL | Consejo Nacional de Telecomunicaciones (Ecuador) |
| CONATEL | Comisión Nacional de Telecomunicaciones (Honduras) |
| CONATEL | Comisión Nacional de Telecomunicaciones (Paraguay) |
| CONATEL | Comisión Nacional de Telecomunicaciones (Venezuela) |
| CONEX | Connectivity Exchange |
| CONP | Connection-Oriented Network Protocol |
| CONS | Connection-Oriented Network Service |
| COO | Cell of Origin |
| COP | Code of Practice |
| COPS | Common Open Policy Service |
| CORBA | Common Object Request Broker Architecture (OMG) |
| CoS | Class of Service |
| COSINE | Cooperation for Open Systems Interconnection Networking in Europe (EUREKA-8) |
| COST | Cooperation for R&D in Science and Technology |
| COT | Central Office Terminal |
| COT | Continuity Test (SS7) |
| COT | Customer Office Terminal |
| CP | Common Practices |
| CPAF | Customer Premise Access Facility |
| CPAS | Cellular Priority Access Services |
| CPB | Cell Priority Bit |
| CPC | Calling Party Category |
| cPCI | Compact Peripheral Component Interconnect |
| CPCS | Call Processing Control System |
| CPCS | Common Part Convergence Sublayer |
| CPE | Customer Premises Equipment |
| CPI-C | Common Programming Interface for Communications |
| CPN | Calling Party Number |
| CPN | Customer Premises Network |
| CPP | Calling Party Pays |
| CPS | Carrier Pre-Selection Service |
| CPS | Cycles per Second (Hertz) |
| CPSS | Control Packet Switching System |
| CPT | Compatibility Test |
| CPU | Central Processing Unit |
| CPU | Computing and Processing Unit |
| CQ | Custom Queuing |
| CQL | Card Query Language |
| CR | Channel Reliability |
| CR | Circuit Reliability |
| CRA | Call Routing Apparatus |
| CRA | Communications Regulatory Agency (Bosnia and Herzegovina) |
| CRAFT | Cooperative Research Action For Technology |
| CRAG | Cellular Radio Advisory Group |
| CRC | Communications Regulation Commission (Bulgaria) |
| CRC | Communications Regulatory Commission (Mongolia) |
| CRC | Cyclic Redundancy Code |
| CREDFACS | Conduit, Raceway, Equipment Ducts, and FACilitieS. (cabling infrastructure elements) |
| CRIMP | Cross Impact Model |
| CRITICOM | Critical Intelligence Communications |
| CRM | Customer Relationship Management |
| CROM | Control Read-Only Memory |
| CRS | Channelised Reserved Services |
| CRS | Customer Reservation System |
| CRT | Cathode Ray Tube |
| CRT | Comisión de Regulación de Telecomunicaciones (Colombia) |
| CRT | Comité de Régulation des Télécommunications (Mali) |
| CRT | Connexion au Réseau Terrestre (French switching equipment) |
| CRTC | Canadian Radio-Television and Telecommunications Commission |
| CS | Carrier Selection |
| CS | Carrier System |
| CS | Circuit Switched |
| CS1 | Capability Set 1 |
| CS2 | Capability Set 2 |
| CSA | Called Sub Answered |
| CSA | Canadian Standards Association |
| CSA | Carrier Serving Area |
| CSC | Carrier Selection Code |
| CSC | Circuit-Switching Centre |
| CSC | Common Signalling Channel |
| CSCW | Computer Supported Cooperative Work |
| CSD | Circuit Switched Data |
| CSDN | Circuit Switched Data Network |
| CSDN | Circuit Switched Digital Network |
| CSE | CAMEL Service Environment |
| CSF | Customer Service Function |
| CSI | Called Subscriber Identification |
| CSI | CAMEL Service Indicator |
| CSI | Carrier Scale Internetworking |
| CSI | Customer-Sited Interconnection |
| CSM | Communications Services Management |
| CSMA | Carrier Sense Multiple Access |
| CSMA/CA | Carrier Sense Multiple Access with Collision Avoidance (LAN) |
| CSMA-CD | Carrier Sense Multiple Access with Collision Detection |
| CSPDN | Circuit Switched Public Data Network |
| CSR | Customer Service Representative |
| CSTA | Computer Supported Telephony Application |
| CSU | Channel Service Unit |
| CSU | Circuit Switching Unit |
| CSU | Customer Service Unit |
| CSV | Circuit Switched Voice |
| CT | Call Transfer |
| CT | Conformance Test |
| CT | Cordless Telecommunications Mobility |
| CT | Cordless Telephone |
| CT | Cross Talk |
| CT-1 | European Analogue Cordless Telephone System |
| CT-2 | Second Generation Digital Cordless Telephone |
| CTC | Call Termination Charge |
| CTD | Cell Transfer Delay |
| CTE | Channel Translation Equipment |
| CTI | Computer Telephony Integration |
| CTIA | Cellular Telecommunications Industry Association |
| CTN | Corporate Telecommunication Network |
| CTO | Commonwealth Telecommunications Organisation |
| C-TPS | Cut-Through Packet Switching |
| CTR | Common Technical Regulations |
| CTS | Clear to Send / Clear to Transmit |
| CTS | Conformance Testing Service |
| CTU | Circuit Terminating Unit |
| CU | Control Unit |
| CUG | Closed User Group |
| CVD | Chemical Vapour Deposition |
| CVSD | Continuously Variable Slope Delta Modulation |
| cw | Carrier Wave |
| cw | Composite Wave |
| cw | Continuous Wave |
| CW | Call Waiting |
| CX | Composite Signalling |
| cxr | Carrier |
| D | |
| D/A | Digital-to-Analogue |
| D/L | Downlink |
| DA | Demand Analysis |
| DA | Destination Address (LAN) |
| DAA | Data Access Arrangement |
| DAB | Digital Audio Broadcasting |
| DAC | Dual Attached Concentrator |
| DACS | Digital Access Cross Connect Service |
| DAI | Digital Audio Interface (104 kbit/s) |
| DAL | Direct Access Line |
| DAM | Dynamic Amplitude Modulation |
| DAMA | Demand Assigned Multiple Access |
| D-AMPS | Digital AMPS (also known as IS-136) |
| DAP | Demand Access Protocol |
| DARPA | Defense Advanced Research Projects Agency (US) |
| DAS | Directory Access System |
| DAS | Dual Attachment Station (FDDI) |
| DASD | Direct Access Storage Device |
| DASS | Digital Access Signalling System |
| DAT | Digital Audio Tape |
| DATV | Digitally Assisted TV |
| DAU | Data Adapter Unit |
| dB | Decibel |
| dBa | Decibels Adjusted |
| DBMS | Database Management System |
| DBS | Direct Broadcasting by Satellite |
| DBS | Database System |
| DC | Direct Current |
| DC | Dry Circuit |
| DCA | Data Communications Agreement |
| DCC | Data Communications Channel |
| DCCH | Dedicated Control Channel |
| DCD | Data Carrier Detect |
| DCE | Data Circuit-Terminating Equipment |
| DCE | Data Communications Equipment |
| DCE | Distributed Computing Environment |
| DCF | Data Communications Function Block (TMN) |
| DCF | Data Count Field |
| DCL | Direct Communications Link |
| DCME | Digital Circuit Multiplication Equipment |
| DCN | Data Communications Network |
| DCOM | Distributed Component Object Model |
| DCOSS | Digital Central Office Switch Simulator |
| DCP | Digital Communications Protocol |
| DCPN | Domestic Customer Premises Network |
| DCPSK | Differentially Coherent Phase-Shift Keying |
| DCS | Digital Cellular System |
| DCS | Digital Communication Systems |
| DCS | Digital Crossconnect System |
| DCS1800 | Digital Communications System 1800 MHz |
| DCT | Discrete Cosine Transform |
| DCU | Digital Concentrator Unit |
| DCU | Distribution and Control Unit |
| DCWV | Direct-Current Working Volts |
| DDBS | Distributed Data Base System |
| DDD | Direct Distance Dialling |
| DDE | Dynamic Data Exchange |
| DDF | Digital Distribution Frame |
| DDI | Direct Dialling In |
| DDM | Digital Data Multiplexer |
| DDM | Distributed Data Management |
| DDN | Defense Data Network (US) |
| DDR | Dial-on-Demand Routing |
| DDR | Double Data Rate |
| DDS | Dataphone Digital Service |
| DDS | Digital Data Service |
| DDS | Direct Digital Synthesis |
| DE | Discard Eligible |
| DECT | Digital Enhanced Cordless Telecommunications |
| DEK | Data Encryption Key |
| DEL | Direct Exchange Line |
| DELTA | Developing European Learning through Technological Advance |
| DEM | Digital Elevation Model |
| Demarc | Demarcation Point |
| demux | Demultiplexer |
| DEN | Document Enabled Networking |
| Dequeue | Double-Ended Queue |
| DES | Data Encryption Standard |
| DES | Direct Extension Select |
| DES | Destination End Station |
| Detem | Detector/Emitter |
| DF | Directional Finding |
| DFC | Data Flow Control |
| DFS | Distributed File System |
| DFSK | Double-Frequency Shift Keying |
| DG | Directorate General (European Commission) |
| DGPS | Differential Global Positioning System |
| DHCP | Dynamic Host Configuration Protocol |
| DHTML | Dynamic Hypertext Mark-up Language |
| DIA | Document Interchange Architecture |
| DID | Direct Inward Dialling |
| DIEL | Advisory Committee on Telecommunications for Disabled and Elderly People (UK) |
| DILIC | Dual Inline Integrated Circuit |
| DIN | Deutsches Institut für Normung (German Standards Institute) |
| DIP | Dual In Line Package (integrated circuits) |
| DIS | Draft International Standard |
| DISA | Direct Inward System Access |
| DISN | Defence Information System Network |
| DISNET | Defence Integrated Secure Network |
| DJSU | Digital Junction Switching Unit |
| DKT | Digital Key Telephone |
| DL | Dial Level |
| DLC | Digital Loop Carrier |
| DLCI | Data-Link Connection Identifier |
| DLCS | Digital Loop Carrier System |
| DLE | Digital Local Exchange |
| DLG | Digital Line Graph |
| DLL | Dynamic Link Library |
| DLSw | Data Link Switching |
| DLTE | Digital Local Tandem Exchange |
| DLU | Digital Line Unit |
| DM | Delta Modulation |
| DM | Disconnected Mode (HDLC) |
| DM | Distributed Management |
| DMA | Direct Memory Access |
| DMA | Data Management Amendment |
| DMB | Dynamic Multipoint Bridging |
| DMC | Desktop Multimedia Conferencing |
| DME | Distance Measuring Equipment |
| DME | Distributed Management Environment |
| DMI | Distributed Management Interface |
| DMOQ | Direct Measures of Quality |
| DMS | Defence Message System |
| DMS | Digital Multiplex Switch |
| DMS | Digital Multiplexer System |
| DMSU | Digital Main Switching Unit |
| DMT | Discrete Multitone |
| DMTF | Desktop Management Task Force |
| DNA | Digital Network Architecture |
| DNIC | Data Network Identification Code (X121) |
| DNIS | Dialled Number Identification Service |
| DNPA | Data Numbering Plan Area |
| DNS | Domain Name Service |
| DNSIX | Department of Defense Intelligence Information System |
| Network Security for Information Exchange (US) | |
| DNU | Digital Networking Unit |
| DO | Design Objective |
| DOCSIS | Data Over Cable Services Interface Specifications |
| DOD | Direct Outward Dialling |
| DoS | Denial of Service |
| DOSE | Direction of Arrival by Signal Elimination |
| DOV | Data Over Voice |
| DOVE | Data Over Voice Equipment |
| DP | Dial Pulsing |
| DP | Dialling Plan |
| DP | Distribution Point |
| DPCM | Differential Pulse Code Modulator |
| DPE | Data Processing Equipment |
| DPIT | Designated Profile Interoperability Testers |
| DPNSS | Digital Private Network Signalling System |
| DPSK | Differential Phase-Shift Keying |
| DQ | Directory Enquiries Service |
| DQDB | Distributed Queue Dual Bus |
| DQPSK | Differential Quadrature Phase Shifting Key |
| DR | Distortion Ratio |
| DRAM | Dynamic Random-Access Memory |
| DRNC | Drift Radio Network Controller |
| DRSI | Destination Station Routing Indicator |
| DRX | Discontinuous Reception |
| DS | Data Set |
| DS | Digital Signal |
| DS | Direct Sequence |
| DS | Direct Support |
| DS | Dual Signalling (Loop-Disconnect and DTMF) |
| DS | Duplex Signalling |
| DSA | Dial Service Assistance |
| DSA | Data Service Unit |
| DSA | Directory Service Agent |
| DSA | Distributed Systems Architecture |
| DSAP | Destination Service Access Point |
| DSB | Double-Sideband |
| DSB-RC | Double-Sideband Reduced Carrier Transmission |
| DSB-SC | Double-Sideband Suppressed-Carrier Transmission |
| DSC | Digital Selective Calling |
| DS-CDMA | Direct-Sequence Code Division Multiple Access |
| DSCS | Defense Satellite Communications System (US) |
| DSE | Data Switching Equipment |
| DSG | Data Systems Group |
| DSI | Detailed Spectrum Investigation of Radio uUsage (as conducted by CEPT/ERO) |
| DSI | Digital Speech Interpolation |
| DSL | Digital Subscriber Line |
| DSLAM | Digital Subscriber Line Access Multiplexer |
| DSMA | Digital Sense Multiple Access |
| DSN | Derived Services Network |
| DSP | Digital Signal Processor |
| DSR | Data Signalling Rate |
| DSRR | Digital Short Range Radio |
| DSS | Dial Selective Signalling |
| DSS | Decision Support System |
| DSS | Digital Subscriber Signalling System (ISDN B-ISDN) |
| DSS | Digital Switched Services |
| DSS | Direct Sequence Spread Spectrum |
| DSS | Direct Station Selection |
| DSSCS | Defence Special Service Communications System |
| DSTE | Data Subscriber Terminal Equipment |
| DSU | Data Service Unit |
| DSU | Digital Service Units |
| DSVD | Digital Simultaneous Voice and Data |
| DT | Data Terminal |
| DT | Dial Tone |
| DTAM | Document Transfer and Manipulation (ISO) |
| DTAP | Direct Transfer Application Part |
| DTE | Data Terminal Equipment |
| DTG | Date-Time Group |
| DTH | Direct-to-Home |
| DTLU | Digital Terminal Line Unit |
| DTM | Digital Terrain Model |
| DTMF | Dual Tone Multi Frequency |
| DTN | Data Transmission Network |
| DTP | Detail Test Plan |
| DTS | Digital Transmission System |
| DTU | Data Transfer Unit |
| DTU | Data Tape Unit |
| DTU | Direct to User |
| DTV | Digital Television |
| DTX | Discontinuous Transmission |
| DUA | Directory User Agent |
| DVB | Digital Video Broadcasting |
| DVL | Direct Voice Link |
| DVM | Data over Voice Multiplexer |
| DVMRP | Distance Vector Multicast Routing Protocol |
| DVRA | Distance Vector Routing Algorithm |
| DVT | Digital Video Terminal |
| DWDM | Dense Wavelength Division Multiplexing |
| DWMT | Discreet Wavelet Multi-Tone |
| DXC | Digital Cross Contact |
| DXI | Data Exchange Interface (ATM SMDS) |
| E | |
| E&M | Ear and Mouth (handset) |
| E&M | Earth and Magnet |
| E&M | Receive and Transmit (signalling) |
| E/O | Electro-Optical Conversion |
| E2E | End-to-End |
| EA | Evaluation Authority |
| EACEM | European Association of Consumer Electronics Manufacturers |
| EAI | Emergency Access Interface |
| EAI | Enterprise Application Integration |
| EAS | Extended Area Service |
| EBC | Element-Based Charging |
| EBIT | European Broadband Interconnection Trial |
| EBITDA | Earnings before Income Tax, Depreciation and Amortisation |
| EBO | Embedded Base Organisation |
| E-Bone | European Backbone (Pan-European Network Backbone Service) |
| EBS | Emergency Broadcast System |
| EBU | European Broadcasting Union |
| EBX | Electronic Branch Exchange |
| EC | Earth Coverage |
| EC | Earth Curvature |
| ECBF | European Citizen’s Band Federation |
| ECC | Electronically Controlled Coupling |
| ECC | Enhanced Call Completion |
| ECCA | European Cable Communication Association |
| ECCM | Electronic Counter-Countermeasures |
| ECET | European Country in Economic Transition |
| ECFRN | European Consultative Forum for Research Networking |
| ECHO | European Commission Host Organisation |
| ECI | European Cooperation in Informatics |
| ECIP | European Cooperation in Information Processing |
| ECITC | European Committee for IT Testing and Certification |
| ECM | Electronic Countermeasures |
| ECMA | European Computer Manufacturers’ Association |
| ECP | European Common Proposal |
| ECS | European Communications Satellite |
| ECSA | European Computing Software Association |
| ECSA | Exchange Carriers’ Standards Association (now ATIS) |
| ECTA | European Competitive Telecommunications Association |
| ECTEL | European Conference of Telecommunications and Electronics Industries |
| ECTEL | National Telecommunications Regulatory Commission (Grenada) |
| ECTF | Enterprise Computer Telephony Forum |
| ECTRA | European Committee for Telecommunications Regulatory Affairs |
| ECTS | Electronic Custom Telephone System |
| ECTUA | European Council of Telecommunications Users’ Association |
| EDC | Error Detection and Correction |
| EDGE | Enhanced Data-Rates for GSM Evolution |
| EDH | Electronic Document Handling |
| EDI | Electronic Data Interchange |
| EDIFACT | Electronic Data Interchange for Administration Commerce and Trade (ANSI) |
| EDM | Electronic Distance Measurement |
| EDNS | Enterprise Defined Network Services |
| EDP | Electronic Data Processing |
| EDTV | Extended-Definition Television |
| EECM | End-to-End Call Manager |
| EEHO | Either End Hop Off |
| EEMA | European Electronic Mail Association |
| EEPROM | Electrically Erasable Programmable Read-Only Memory |
| EEROM | Electronically Erasable Read-Only Memory |
| EESS | Earth Exploration-Satellite Service |
| EETT | National Committee of Communications & Posts (Greece) |
| EF&I | Engineering, Furnishing and Installation |
| EFCI | Explicit Forward Congestion Indication |
| EFF | Electronic Frontier Foundation |
| EFR | Enhanced Full Rate |
| EFS | End of Frame Sequence (LAN) |
| EFT | Electronic Funds Transfer |
| EFTA | European Free Trade Association |
| EFTPOS | Electronic Funds Transfer at Point of Sale |
| EGP | Exterior Gateway Protocol |
| EGSM | Extended Global System for Mobile Communications |
| EH | Electronic Highways |
| EHF | Extremely High Frequency |
| EI | Engineering Instruction |
| EI | Expansion Interface |
| EIA | Electronics Industry Association |
| EIB | European Investment Bank |
| EICTA | European Information Communications Technology Industry Association |
| EIR | Equipment Identity Register |
| EIRP | Effective or Equivalent Isotropically Radiated Power |
| EIS | Emergency Information System |
| EISA | Extended Industry Standard Architecture |
| EIUF | European ISDN User Forum |
| EKTS | Electronic Key Telephone Sets |
| EL | Elevation |
| ELAN | Emulated LAN |
| ELB | Emergency Location Beacon |
| EL-display | Electro-Luminescent Display |
| ELECTRO- OPTINT | Electro-Optical Intelligence |
| ELF | Extremely Low Frequency |
| ELINT | Electronics/Electromagnetic Intelligence |
| ELMI | Enhanced Local Management Interface |
| ELR | Earth Leg Recall |
| ELSEC | Electronics Security |
| ELT | Emergency Locator Transmitter |
| EMA | Electronic Messaging Association |
| EMA | Enterprise Management Architecture |
| EMAG | ETSI MIS Advisory Group |
| EMC | Electromagnetic Compatibility |
| EMCON | Emission Control |
| EMD | Equilibrium Mode Distribution |
| EME | Electromagnetic Environment |
| EMI | Electromagnetic Interference |
| EML/EMS | Element Management Layer/ Element Management Service |
| EMP | Electromagnetic Pulse |
| EMR | Electromagnetic Radiation |
| EMRP | Equivalent Monopole Radiated Power |
| EMS | Electronic Message System |
| EMS | Enhanced Messaging Services |
| EMS | Expanded Memory Specification |
| EMSEC | Emanations Security |
| EMU | Electromagnetic Unit |
| EMV | Electromagnetic Vulnerability |
| EMW | Electromagnetic Warfare |
| EMW | Electromagnetic Wave |
| EN | Norme Européenne (European Standard) |
| ENF | European Numbering Forum |
| ENFIA | Exchange Network Facilities For Interstate Access (US) |
| ENG/OB | Electronic News Gathering/Outside Broadcast |
| ENO | European Numbering Office |
| ENS | Enhanced Network Services |
| ENS | Enterprise Network Services |
| ENSO | ETSI National Standardisation Organisations (ETSI) |
| ENV | European Pre-standard |
| EO | End Office |
| EO | Executive Order |
| EOC | Embedded Operation Channel |
| EOD | End of Data |
| EOF | End of File |
| EOL | End of Line |
| EOM | End of Message |
| EOP | End of Program |
| EOP | End Output |
| EOS | End of Selection |
| EOT | End of Tape |
| EOT | End of Transmission |
| EOTC | European Organisation for Testing and Certification |
| EOW | Engineering Orderwire |
| EPD | Early Packet Discard |
| EPI | External Provisioning Interface |
| EPIRB | Emergency Position Indicating Radio Beacons |
| EPMU | Equal Proportionate Mark-Up |
| EPOST | Electronic Point of Sale Terminal |
| EPROM | Erasable Programmable Read-Only Memory |
| EPS | End of Frame Sequence (LAN) |
| EPSCS | Enhanced Private Switched Communications System |
| ER | Earth Recall |
| ER | Explicit Rate |
| ER | Essential Requirement |
| ERC | European Radiocommunications Committee |
| ERDF | European Regional Development Fund |
| ERG | European Regulators’ Group |
| ERL | Echo Return Loss |
| ERLINK | Emergency Response Link |
| ERMES | European Radio Message System (standard for pagers) |
| ERO | European Radiocommunications Office |
| ERP | Effective Radiated Power |
| ERP | Enterprise Resource Planning |
| ES | End System |
| ES | Expert System |
| ESA | European Space Agency |
| ESAC | Emergency Switch Assistance Centre |
| ESB | European Standardisation Board |
| ESC | Enhanced Satellite Capability |
| ESC | European Standardisation Council |
| ESCON | Enterprise System Connection (IBM) |
| ESD | Electrostatic Discharge |
| ESD | European Standards Database |
| ESDI | Enhanced Small Device Interface |
| ESF | European Science Foundation |
| ESF | Extended SuperFrame |
| ESI | End System Identifier (ATM ISO) |
| ESIG | European SMDS Interest Group |
| ESM | Electronic Warfare Support Measures |
| ESMR | Enhanced Specialised Mobile Radio |
| ESMTP | Extended Simple Mail Transfer Protocol |
| ESN | Equipment Serial Number |
| ESO | European Standardisation Organisation |
| ESP | EBIT Service Project |
| ESP | Encapsulating Security Payload (IPSec security protocol) |
| ESP | Enhanced Service Provider |
| ESP | Extended Services Processor |
| ESPRIT | European Strategic Programme for Research and Development |
| ESRP | Ente Regulador de los Servicios Públicos (Panama) |
| ESS | Electronic Switching System |
| ESS | European Standardisation System |
| ETACS | Extended Total Access System |
| ETCI | Electro-Technical Council of Ireland |
| ETD | Extension Trunk Dialling |
| E-TDMA | Enhanced TDMA |
| ETN | Electronic Tandem Network |
| ETNO | Association of European Public Telecommunications Network Operators |
| ETO | European Telecommunications Office |
| ETP | European Telecommunications Platform |
| ETR | ETSI Technical Report |
| ETS | Emergency Telecommunications Services |
| ETS | European Telecommunications Standard |
| ETSA | European Telecommunication Services Association |
| ETSI | European Telecommunications Standard Institute |
| EUMETSAT | European Meteorological Satellite Organisation |
| EUREKA | European Research Co-operation Agency |
| EUREKA-95 | European Research Project on HDTV |
| EURESCOM | European Institute for Research and Strategic Studies in Telecommunications |
| EUROBIT | European Association of Manufacturers of Business Machines and Data Processing Equipment |
| EurOSINET | European OSI Network |
| EUSIDIC | European Association of Information Services |
| EUTELSAT | European Telecommunications Satellite Organisation |
| EV | European Videocommunications |
| EW | Electronic Warfare |
| EWOS | European Workshop for Open Systems |
| EWP | ETSI Work Programme |
| EXCSA | Exchange Carriers Standards Association |
| EXZ | Excessive Zeros |
| F | |
| F | Frequency |
| FAA | Federal Aviation Administration (US) |
| FAC | Fully Allocated Costs |
| FACCH | Fast Association Control Channel |
| FAN | Flexible Access Network |
| FAQ | Frequently Asked Questions |
| FAS | Frame Alignment Sequence (T-1 and E1) |
| FB | Framing Bit |
| FC | Fibre Channel |
| FC | Frame Control |
| FC | Functional Component |
| FCAPS | Fault, Configuration, Accounts, Performance, Security (ISO) |
| FCC | Federal Communications Commission (USA) |
| FCCH | Forward Control Channel |
| FCS | Federation of Communications Services (UK) |
| FCS | Frame Check Sequence |
| FD | Full Duplex |
| FDC | Fully-Distributed Costs |
| FDD | Frequency Division Duplex |
| FDDI | Fibre Distributed Data Interface |
| FDHM | Full Duration at Half Maximum |
| FDM | Frequency Division Multiplexing |
| FDMA | Frequency Division Multiple Access |
| FDMMA | Frequency Division Multiplexing Multiple Access |
| FDP | Floor Distribution Point |
| FDX | Full Duplex |
| FEC | Forward Error Correction |
| FECN | Forward Explicit Congestion Notification |
| FED-STD | Federal Standard (US) |
| FEI | Federation of the Electronics Industry (UK) |
| FEMA | Federal Emergency Management Agency (US) |
| FEP | Front-End Processor |
| FET | Field Effect Transistor |
| FEXT | Far End Cross Talk |
| FFSK | Fast FSK |
| FFT | Fast Fourier Transform |
| FG | Feature Group |
| FH | Frequency-Hopping |
| FH/DS | Frequency-Hopping Direct Sequence |
| FHSS | Frequency-Hopping Spread Sequence |
| FIAG | Framework Interconnection Agreement Guidelines |
| FIB | Focused Ion Beam |
| FICORA | Finnish Communications Regulatory Authority |
| FIFO | First In/First Out |
| FIPS | Federal Information Processing Standards |
| FIR | Finite Impulse Response |
| FIRMR | Federal Information Resources Management Regulations |
| FITL | Fibre In The Loop |
| FLOPS | Floating-Point Operations Per Second |
| FLS | Fallback/Fall-Forward Line Sensing |
| FLT | Full Line Terminal Multiplexer |
| FM | Frequency Modulation |
| FM | Function Management |
| FMC | Fixed Mobile Convergence |
| FMH | Function Management Header (SNA) |
| FMS | Fraud Management System |
| FNC | Federal Networking Council (US) |
| FO | Fibre Optic |
| FOC | Final Operational Capability |
| FOC | Full Operational Capability |
| FOD | Fax on Demand |
| FoIP | Fax over Internet Protocol |
| FOIRL | Fibre Optic Interrepeater Link |
| FOT | Frequency of Optimum Transmission |
| FOTP | Fibre Optic Transmittance Procedure |
| FOTS | Fibre Optics Transmission Systems |
| FPD | Flat Panel Display |
| FPIS | Forward Propagation Ionospheric Scatter |
| FPLMTS | Future Public Land Mobile Telecommunication System |
| FR | Frame Relay |
| FR | Frequency Response |
| FRAD | Frame Relay Assembler/ Disassembler |
| FRAD | Frame Relay Access Device |
| FRASM | Frame Relay Access Service Module |
| FRBS | Frame Relay Bearer Service |
| FRF | Frame Relay Forum |
| FRIACO | Flat Rate Internet Access Call Origination |
| FRM | Functional Reference Model |
| FRS | Frame Relay Service |
| FRS | Frame Relay Switch |
| FSAN | Full Service Access Network |
| FSDPSK | Filtered Symmetric Differential Phase-Shift Keying |
| FSK | Frequency Shifting Sequence |
| FSL | Flexible Service Logic |
| FSS | Fixed-Satellite Service |
| FT | Fibre Optic T-Carrier |
| FT1 | Fractional T1 |
| FTAM | File Transfer Access & Management |
| FTF | Federal Telecommunications Fund (US) |
| FTP | File Transfer Protocol |
| FTPF | File Transfer Protocol Filter |
| FTS | Federal Telecommunications System (US) |
| FTSC | Federal Telecommunications Standards Committee (US) |
| FTTB | Fibre to the Building |
| FTTC | Fibre to the Curb (North America) |
| FTTCab | Fibre to the Cabinet |
| FTTEx | Fibre to the Exchange |
| FTTH | Fibre to the Home |
| FTTK | Fibre to the Kerb (UK) |
| FTTN | Fibre to the Neighbourhood |
| FUNI | Frame User-to-Network Interface (ATM) |
| FVC | Forward Voice Channel |
| FWA | Fixed Wireless Access |
| FWHM | Full Width At Half Maximum |
| FWM | Four Wave Mixing |
| FX | Fixed Service |
| FX | Foreign Exchange Service |
| FXO | Foreign Exchange Office |
| FXS | Foreign Exchange Station |
| G | |
| G.lite | G.992.2 Standard for Asymmetric DSL Technology |
| G/T | Antenna Gain-to-Noise-Temperature |
| GA | General Assembly (ETSI) |
| GAC | Governmental Advisory Committee (ICANN) |
| GAN | Global Area Network |
| GAP | Generic Access Profiles |
| GASP | Gatekeeper Synchronisation Protocol |
| GATT | Global Agreement on Tariffs and Trade |
| GBH | Group Busy Hour |
| GCAC | Generic Connection Admission Control |
| GCC | Generic Conference Control |
| GCCC | Global Customer Care Center |
| GCRA | Generic Call Rate Algorithm |
| GDF | Group Distribution Frame |
| GDS | Generic Digital Services |
| GEA | Gigabit Ethernet Alliance |
| GEN | Global European Network |
| GEO | Geostationary Earth Orbit |
| GETS | Government Emergency Telecommunications Service |
| GFC | Generic Flow Control (ATM) |
| GFI | Genera Format Identifier (X25) |
| GGCL | Government-to-Government Communications Link |
| GGP | Gateway-to-Gateway Protocol |
| GGSN | Gateway GPRS Support Node |
| GIBN | Global Interoperability of Broadband Networks |
| GII | Global Information Infrastructure |
| GIO | General Interest Obligations |
| GIO | Generic Interface for Operations (SMDS) |
| GIS | Geographical Information System |
| GIX | Global Internet eXchange |
| GLONASS | Global Navigation Satellite System |
| GMDSS | Global Maritime Distress and Safety System |
| GMPCS | Global Mobile Personal Communication by Satellite |
| GMRS | General Mobile Radio Service |
| GMSC | Gateway Mobile Services Switching Centre |
| GMSK | Gaussian Minimum Shifting Keying |
| GNCC | Georgian National Communications Commission |
| GNOC | Global Network Operation Centre |
| GNS | Get Nearest Server |
| GOF | Glass Optical Fibre |
| GoS | Grade of Service |
| GOSIP | Government Open Systems Interconnection Profile |
| GPIB | General Purpose Interface Bus |
| GPRS | General Packet Radio Service |
| GPS | Global Positioning System |
| GR | GPRS Register |
| GRE | Generic Routing Encapsulation |
| GRX | GPRS Roaming Exchange |
| GS | Ground-Start Signalling |
| GSA | General Services Administration (US) |
| GSA | Global Mobile Suppliers Association |
| GSA | GSM System Area |
| GSLB | Groupe Spécial Large Bande (CEPT group on broadband telecommunications) |
| GSM | Global System for Mobile (second-geration mobile telephony standard) |
| GSM MS | GSM Mobile Station |
| GSM PLMN | GSM Public Land Mobile Network |
| GSM900 | Global System for Mobile 900 MHz |
| GSMP | Global Service Management Platform |
| GSM-R | GSM for Railways |
| GSN | GPRS Support Node |
| GSO | Geostationary Orbit |
| GSS | Generic Service State |
| GSS | Group Switching Subsystem |
| GSTN | General Switched Telephone Network |
| GTD | Geometric Theory of Diffraction |
| GTP | Government Telecommunications Programme |
| GTP | GPRS Tunnelling Protocol |
| GTR | General Technical Requirements (Russia) |
| GTS | Government Telecommunications System |
| GVPN | Global Virtual Private Network |
| H | |
| H Channel | High-Speed Channel (ISDN) |
| HACMP | High-Availability Cluster Multiprocessing |
| HARCENELEC | Agreement for Electrical Cords and Cables |
| HBN | High Bandwidth Networking |
| HBS | Home Base Station |
| HCA | Historic Cost Accounting |
| HCDS | High-Capacity Digital Services |
| HCM | High Capacity Multiplexing |
| HCS | Hard Clad Silica [fibre] |
| HCSPR | Hundred Call Seconds Per Hour |
| HCV | High Capacity Voice |
| HD | Half Duplex |
| HD | Harmonic Distortion |
| HDDV | High Definition Digital Video |
| HDF | Hand-Over Distribution Facility |
| HDLC | High-Level Data Link Control |
| HDML | Handheld Device Markup Language |
| HDSL | High-Data-Rate Digital Subscriber Line |
| HDT | Host Digital Terminal |
| HDTM | Half-Duplex Transmission Module (X25) |
| HDTV | High Definition Television |
| HDWDM | High Density Wavelength Division Multiplex |
| HDX | Half-Duplex |
| HEC | Header Error Control |
| HEHO | Head End Hop Off |
| HEMP | High-Altitude Electromagnetic Pulse |
| HEPnet | High-Energy Physics Network |
| HERF | Hazards of Electromagnetic Radiation to Fuel |
| HERO | Hazards of Electromagnetic Radiation to Ordnance |
| HERP | Hazards of Electromagnetic Radiation to Personnel |
| HES | Home Electronic System(s) |
| HF | High Frequency |
| HFC | Hybrid Fibre/Coax |
| HFDF | High-Frequency Distribution Frame |
| HIC | Head-End Interface Converter |
| HiCap | High-Capacity Digital Services |
| HIPERLAN | High Performance Local Area Network |
| HIPPI | High Performance Parallel Interface |
| HIS | Hospital Information System |
| HLC | High Layer Compatibility (ISDN) |
| HLC | High Level Committee (ITU) |
| HLL | High Level Language |
| HLR | Home Location Register |
| HNPA | Home Numbering Plan Area |
| HOSTID | Host Identifier |
| HP/PN | Hybrid Private/Public Networking |
| HPC | High Probability of Completion |
| HPLMN | Home Public Land Mobile Network |
| HPPI | High-Performance Parallel Interface |
| HPR | High Performance Routing |
| HS | High Speed |
| HSC | Hierarchical Cell Structure |
| HSCSD | High Speed Circuit Switched Data |
| HSCSD | High Speed Circuit Switched Data |
| HSLAN | High Speed LAN |
| HSPSD | High-Speed Packet Switched Data |
| HSSI | High-Speed Serial Interface (ANSI) |
| HTML | Hypertext Markup Language |
| HTTP | Hypertext Transfer Protocol (IETF) |
| HV | High Voltage |
| HW | Hardware |
| I | |
| I&A | Identification and Authentication |
| I&C | Installation and Checkout |
| I&M | Installation and Maintenance |
| I/F | Interface |
| I/O | Input/Output |
| IA | International Alphabet [CCITT] |
| IAB | Internet Architecture Board |
| IAC | Install and Commission |
| IACS | Integrated Access and Crossconnect System |
| IAFIS | Integrated Automated Fingerprint Identification System |
| IAHC | Internet International Ad Hoc Committee |
| IAM | Initial Address Message (SS7) |
| IANA | Internet Address Naming Authority |
| IARU | International Amateur Radio Union |
| IBC | Integrated Broadband Communication |
| IBCN | Integrated Broadband Communications Network |
| IBN | Integrated Broadband Network |
| IBS | International Business Service (INTELSAT) |
| IC | Incoming |
| IC | Integrated Circuit |
| IC | Interconnect |
| ICANN | Internet Corporation for Assigned Names and Numbers |
| ICASA | Independent Communications Authority of South Africa |
| ICCB | Internet Control and Configuration Board |
| ICD | Internal Cable Distribution |
| ICD | International Code Designator (ISO) |
| ICGB | Institut des Communications de la Guinée-Bissau |
| ICI | Incoming Call Identification |
| ICI | Intercarrier Interface (SMDS) |
| ICI | Interexchange Carrier Interface (US) |
| ICMP | Internet Control Message Protocol |
| ICNI | Integrated Communications, Navigation, and Identification |
| ICP | Internet Control Protocol |
| ICR | Initial Cell Rate |
| ICR | Intelligent Call Routing |
| ICS | Implementation Conformance Statement |
| ICS | Intelligent Calling System |
| ID | Identification |
| ICSA | International Computer Security Association |
| ICT | Information and Communication Technologies |
| ICTA | Information and Communication Technologies Authority (Mauritius) |
| ICW | Interrupted Continuous Wave |
| ID | Identification |
| IDA | Infocomm Development Authority of Singapore |
| IDA | Integrated Data Access |
| IDC | Insulation Displacement Connection |
| IDD | International Direct Dialling |
| IDDD | International Direct Distance Dialling |
| IDDD | International Direct Dialling Designator |
| IDEN | Integrated Dispatch Enhanced Network |
| IDF | Intermediate Distribution Frame |
| IDI | Initial Domain Identifier (ISO) |
| IDLC | Integrated Digital Loop Carrier (Telephony) |
| IDN | Integrated Digital Network |
| IDNX | Integrated Digital Network Exchange |
| IDP | Initial Domain Part |
| IDP | Internet Datagram Protocol |
| IDPR | Inter-Domain Policy Routing |
| IDR | Intermediate Data Rate/Intelsat Digital Route |
| IDS | Intrusion Detection System |
| IDTV | Improved-Definition Television |
| IE | Information Element |
| IEC | Interconnection Extension Circuit |
| IEC | Interexchange Carrier |
| IEC | International Electrotechnical Commission |
| IEE | Institution of Electrical Engineers (UK) |
| IEEE | Institute of Electrical and Electronic Engineers (UK) |
| IEPG | Internet Engineering Planning Group |
| IES | Industry Executive Subcommittee |
| IES | Information Exchange Services |
| IESG | Internet Engineering Steering Group |
| IETF | Internet Engineering Task Force |
| IETF | Internet Engineering Task Force |
| I-ETS | Interim European Telecommunications Standard |
| IF | Intermediate Frequency |
| IFFT | Inverse FFT |
| IFIP | International Federation for Information Processing |
| IFL | International Frequency List |
| IFRB | International Frequency Registration Board (now Radio Regulations Board ) |
| IFS | Ionospheric Forward Scatter |
| IGMP | Internet Group Management Protocol |
| IGP | Internet Gateway Protocol |
| IGRP | Interior Gateway Routing Protocol |
| IHL | Internet Header Length (IP) |
| IHS | In-House System |
| IIR | Infinite Impulse Response |
| IIT | Integrated Information Transport |
| IITF | Information Infrastructure Task Force |
| IKE | Internet Key Exchange |
| ILD | International Long Distance |
| ILEC | Incumbent Local Exchange Carrier (US) |
| ILR | Institut Luxembourgeois de Régulation |
| IM | Instant Messaging |
| IM | Intensity Modulation |
| IM | Intermodulation |
| IMA | Invere Multiplexing over ATM |
| IMAP | Internet Message Access Protocol |
| IMCC | ISDN Management and Co-ordinating Committee |
| IMD | Intermodulation Distortion |
| IME | International Mobile Station Equipment Identity |
| IMEI | International Mobile Equipment Identity |
| IMN | Intelligent Mobile Network |
| IMO | International Maritime Organisation |
| IMP | Interface Message Processor |
| IMP | Intermodulation Products |
| IMS | Internet Management System |
| IMSI | International Mobile Station Identity |
| IMSI | International Mobile Subscriber Identity |
| IMT | International Mobile Telecommunications |
| IMTC | International Multimedia Conferencing Consortium |
| IMTS | Improved Mobile Telephone Service |
| IMUX | Intelligent Multiplexer |
| IMUX | Inverse Multiplexer |
| IN | Intelligent Network (AIN) |
| INA | Information Networking Architecture |
| INACOM | Institut Angolais des Communications (Angola) |
| INAP | Intelligent Network Application Part |
| INCA | Inter Network Call Accounting system |
| INCM | Instituto Nacional das Comunicações de Moçambique (Mozambique) |
| INE | Intelligent Network Element |
| INFOSEC | Information Systems Security |
| INLSP | Integrated Net Layer Security Protocol |
| INMARSAT | International Marine Satellite Organisation |
| INMS | Integrated Network Management System |
| INS | Inertial Navigation System |
| INTAP | Interoperability Technology Association for Information Processing |
| INTELSAT | International Satellite Organisation |
| INTT | Instance Nationale des Télécommunications (Tunisia) |
| INTUG | International Telecommunications User Group |
| INWATS | Inward Wide-Area Telephone Service |
| IO | Input/Output |
| IOC | Integrated Optical Circuit |
| IOC | Independent Operating Company (US) |
| IOC | Initial Operational Capability |
| IOC | Input-Output Controller |
| IOC | Inter Office Channel |
| IOCC | I/O Channel Controller |
| ION | Integrated Optical Network |
| IONL | Internal Organisation of the Network Layer |
| IOPS | Internet Operators’ Providers Services |
| IOT | Inter-Office Trunk |
| IP | Intellectual Property |
| IP | Intelligent Peripheral |
| IP | Interexchange Plant |
| IP | Internet Protocol |
| IPA | Intermediate Power Amplifier |
| IPC | Information Processing Center |
| IPC | Interprocess Communication |
| IPCP | Internet Protocol Control Protocol |
| IPM | Impulses Per Minute |
| IPM | Interference Prediction Model |
| IPM | Internal Polarisation Modulation |
| IPM | Interruptions Per Minute |
| IPN | Intelligent Peripheral Node |
| IPNS | ISDN PBX Networking Specification |
| IPoATM | Internet Protocol over ATM |
| IPR | Intellectual Property Rights |
| IPS | Instructions Per Second |
| ips | Interruptions Per Second |
| IPSec | Internet Protocol Security |
| IPSO | IP Security Option |
| IPT | Internet Protocol Telephony |
| IPv6 | Internet Protocol Version 6 |
| IPX | Internetwork Packet Exchange (NetWare) |
| IQF | Intrinsic Quality Factor |
| IR | Infrared |
| IR | Internet Registry |
| IRAC | Interdepartment Radio Advisory Committee |
| IRAS | Internet Routing and Access Service |
| IRB | Integrated Routing and Bridging |
| IRC | International Record Carrier |
| IRC | Internet Relay Chat |
| IrDA | Infrared Data Association |
| IRG | Independent Regulators’ Group (Europe) |
| IrLAN | Infrared LAN |
| IrLAP | Infrared Link Access Protocol |
| IRN | Intermediate Routing Node |
| IRP | Independent Routing Processor |
| IRPA | International Radiation Protection Association |
| IRQ | Interrupt Request |
| IRR | Internal Rate of Return (Financial Modelling) |
| IRSG | Internet Research Steering Group |
| IRT | Integrated Rural Telematics |
| IRTA | Integrated Regional Telematics Architecture |
| IRTF | Internet Research Task Force |
| IS | In-Service |
| IS | Information Systems |
| IS | Interim Standard (ISO) |
| IS | Intermediate System (ISO) |
| ISA | Industry Standard Architecture |
| ISAC | Information Society Activity Centre (European Commission) |
| ISB | Independent Side Band |
| ISC | International Switching Centre |
| ISD | International Subscriber Dialling (now IDD) |
| ISDN | Integrated Services Digital Network |
| ISE | Integrated Service Engineering |
| ISI | In Span Interconnection |
| IS-IS | Intermediate System-to-Intermediate System |
| ISL | Inter-Switch Link |
| ISM | Industrial, Scientific, and Medical (applications and frequency bands) |
| ISM | Internetwork Status Monitor |
| ISM | ISDN Standards Management |
| ISN | Information Systems Network |
| ISO | International Organisation for Standardisation |
| ISOC | Internet Society |
| ISP | Internet Service Provider |
| IS-PBX | Integrated Services Private Branch Exchange |
| ISPO | Information Society Promotion Office (European Commission) |
| ISR | International Simple Resale |
| ISSI | Inter-Switching System Interface |
| ISUP | ISDN User Part |
| ISV | Independent Software Vendor |
| ISVR | International Simple Voice Resale |
| IT | Information Technology |
| IT | Information Type |
| IT&T | Information Technologies & Telecommunications |
| ITA | International Telegraph Alphabet |
| ITC | International Teletraffic Congress |
| ITM | Isochronous Transmission |
| ITN | Independent Telecommunication Network |
| ITR | Intelligent Text Retrieval |
| ITS | Insertion Test Signal |
| ITS | Institute for Telecommunication Sciences |
| ITSC | Interregional Telecommunications Standards Conference |
| ITSO | International Telecommunications Satellite Organisation |
| ITSP | Internet Service Telephony Provider |
| ITST | National IT and Telecom Agency (Denmark) |
| ITSTC | Information Technology Steering Committee |
| ITT&B | Information Technologies Telecommunications & Broadcasting |
| ITU | International Telecommunications Union |
| ITU-R | International Telecommunication Union- Radiocommunications |
| ITU-T | International Telecommunication Union- Telecommunications |
| ITUSA | Information Technology Users Standards Association |
| IUC | Interconnection Usage Charge |
| IVDM | Integrated Voice Data Multiplexer |
| IVDS | Interactive Video Data Services |
| IVDT | Integrated Voice and Data Terminal |
| IVN | Intervening Network (ETSI) |
| IVPN | International Virtual Private Networks |
| IVR | Interactive Voice Response |
| IVS | Interactive Video Service |
| IWF | Inter-Working Function |
| IWU | Inter-Working Unit (ETSI TC BT) |
| IXC | Inter-Exchange Mileage |
| IXC | Inter-Exchange Carrier (US) |
| IXIT | Implementation Extra Information for Testing |
| J | |
| JADSL | ADSL for ISDN |
| JANET | Joint Academic Network (UK) |
| JCCR | Joint Committee on Cellular Roaming |
| JCG | Joint Co-ordination Group (CEN/CENELEC/ETSI) |
| JDBC | Java Database Connectivity |
| JDC | Japan’s Digital Cellular |
| JEEC | Joint ECMA ETSI Programme Committee |
| JIT | Just In Time |
| JPEG | Joint Photographic Experts Group (ISO) |
| JRTIC | Joint Radiophone Technical Interfaces Group |
| JSC | Joint Spectrum Centre (US) |
| JTACS | Japanese TACS System |
| JTC | Joint Technical Committee (EBU/ETSI and ISO/IEC) |
| JTCG | Joint Technical Co-ordination Group |
| JTM | Job Transfer and Management |
| JUNET | Japan UNIX Network Nationwide |
| K | |
| K/D | Keyboard/Display |
| KA | Keep Alive Signal |
| Kbps | Kilo bits per second |
| KBS | Knowledge-Based System |
| KCC | Korea Communications Commission |
| KDC | Key Distribution Centre |
| KDR | Keyboard Data Recorder |
| KDS | Key Distribution Service |
| kHz | Kilohertz |
| KMC | Key Management Centre |
| KS | Kearny Specification (US) |
| KSR | Keyboard Send/Receive Device |
| KSU | Key Service Unit |
| kT | Noise Power Density |
| KTS | Key Telephone System |
| KTU | Key Telephone Unit |
| L | |
| l/m | Lines per Minute |
| L1 | Layer 1 (physical layer) |
| L2 | Layer 2 (data link layer) |
| L3 | Layer 3 (network layer) |
| LADS | Local Area Data Service |
| LAI | Location Area Identification or Identity |
| LAMs | Line Adaptor Modules |
| LAN | Local Area Network |
| LANE | LAN emulation |
| LANS | Local Area Network Services |
| LAP | Link Access Procedure (X25) |
| LAP-B | Link Access Protocol-Balanced |
| LAPD | Link Access Procedure for the D-channel (ISDN) |
| LAPF | Link Access Procedure to Frame mode bearer services (FR ISDN) |
| LAPM | Link Access Procedure for Modems (V42) |
| LAPX | Link Access Procedure Half-Duplex (X32) |
| LASS | Local Area Signalling Services |
| LATA | Local Access and Transport Area (US) |
| LATS | Loop Access Test System |
| LB | Local Battery |
| LBA | Location Based Advertising |
| LBO | Line Buildout |
| LBS | Location-Based Services |
| LC | Limited Capability |
| LCD | Liquid Crystal Display |
| LCI | Logical Channel Identifier |
| LCM | Line Concentrator Module |
| LCN | Local Communication Network |
| LCN | Logical Channel Number (X25) |
| LCP | Link Control Protocol |
| LCR | Least Cost Routing |
| LCV | Line Code Violation |
| LD | Long Distance |
| LD | Loop Dial |
| LD | Loop Disconnect |
| LDC | Long Distance Carrier |
| LDCELP | Low-Delay Code Excited Linear Prediction Compression |
| LDDI | Local Distributed Data Interface (ANSI) |
| LDM | Limited Distance Modem |
| LDN | Listed Directory Number |
| LE | Local Exchange (ISDN) |
| LE_ARP | LAN Emulation Address Resolution Protocol Protocol |
| LEC | LAN Emulation Client. |
| LEC | Local Exchange Carrier |
| LECS | LAN Emulation Configuration Server |
| LEO | Low Earth Orbit |
| LEOS | Low Earth Orbit Satellites |
| LES | LAN Emulation Server |
| LF | Low Frequency |
| LFB | Look-Ahead-For-Busy |
| LFR | Less Favoured Region |
| LI | Length Indicator |
| LIDB | Line Information Database (ISDN) |
| LIFO | Last In First Out |
| LIMO | Limited Mobility |
| LIS | Logical IP Subnet |
| LJU | Line Jack Unit |
| LL | Leased Lines |
| LLB | Line LoopBack |
| LLC | Low Layer Compatibility (ISDN) |
| LLC | Logical Link Control |
| LLU | Local Loop Unbundling (see also ULL) |
| LMDS | Local Multipoint Distribution System |
| LMF | Language Media Format |
| LMI | Local Management Interface |
| LMOS | Loop Maintenance Operations System |
| LMR | Land Mobile Radio |
| LMS | Location and Monitoring Service |
| LMSS | Land Mobile Satellite Service |
| LMT | Local Maintenance Terminal |
| LNA | Launch Numerical Aperture |
| LNA | Low Noise Amplifier |
| LNB | Low Noise Block |
| LNM | LAN Network Manager |
| LNP | Local Number Portability |
| LNR | Last Number Redial |
| LO | Local Oscillator |
| LOB | Line Of Bearing |
| LOF | Lowest Operating Frequency |
| LORAN | Long-Range Radio Aid To Navigation System |
| LOS | Line Of Sight |
| LOS | Loss Of Signal |
| LP | Linear Programming |
| LP | Linearly Polarised |
| LP | Linking Protection |
| LP | Log-Periodic |
| LPA | Linear Power Amplifier |
| LPC | Linear Predictive Coding |
| LPD | Low Power Device |
| LPD | Low Probability Of Detection |
| LPI | Low Probability of Intercept |
| LQA | Link Quality Analysis |
| LRAIC | Long Run Average Incremental Costs |
| LRC | Longitudinal Redundancy Check |
| LRIC | Long Run Incremental Costs |
| LS | Loop-Start Signalling |
| LSB | Lower Sideband, Least Significant Bit |
| LSI | Large Scale Integrated or Integration |
| LSI | Line Status Indication |
| LSL | Link Support Layer |
| LSPSD | Low-Speed Packet Switched Data |
| LSRP | Link-State Routing Protocol |
| LST | Loudspeaking Telephone |
| LT | Line Termination |
| LTA | Lesotho Telecommunications Authority |
| LTC | Line Traffic Coordinator |
| LTE | Line Terminating Equipment |
| LTU | Line Termination Unit |
| LU | Logical Unit (IBM) |
| LUF | Lowest Usable Frequency |
| LULT | Line-Unit-Line Termination |
| LUNI | LAN Emulation User-to-Network Interface |
| LUNT | Line-Unit-Network Termination |
| LV | Low Voltage |
| LVD | Low Voltage Directive (European Union) |
| M | |
| M/W | Microwave |
| MA | Medium Adaptor |
| MAC | Media Access Control |
| MAC | Medium Access Control (protocol layering context) |
| MAC | Move, Add, and Change |
| MAC | Multiplexed Analogue Components |
| MAC | Standards Multiplex of Analogue Components (time division multiplex technique for TV/HDTV transmission) |
| MACRA | Malawi Communications Regulatory Authority |
| MAE | Metropolitan Access Exchange |
| MAE | Metropolitan Area Exchange |
| MAF | Management Application Function (TMN) |
| MAI | Mobile Allocation Index |
| MAN | Metropolitan Area Networks |
| MAP | Manufacturing Automation Protocol |
| MAP | Mobile Application Part |
| MAP/TOP | Manufacturing Automation Protocol/Technical and Office Protocol |
| MAPI | Messaging Applications Programming Interface (Microsoft) |
| MAPS | Maps Application Provisioning System |
| MAR | Memory Address Register |
| MARS | Multicast Address Resolution Server |
| Maser | Microwave Amplification by the Stimulated Emission of Radiation |
| MAT | Maintenance Acceptance Test |
| MATSE | Mobile Automatic Telephone System - Europe |
| MAU | Maximum Attachment Unit |
| MAU | Medium Access Unit |
| MAU | Medium Attachment Unit (Ethernet) |
| MAU | Multistation Access Unit |
| MBFT | Multipoint Binary Transfer File |
| M-Bone | Multimedia Backbone |
| Mbps | Megabits per second |
| MBR | Maritime Business Radio |
| MBS | Mobile Broadband System |
| MC | Management Centre |
| MC | Message Centre |
| MCA | Malta Communications Authority |
| MCA | Micro Channel Architecture |
| MCC | Maintenance Control Circuit |
| MCC | Mobile Country Code |
| MCCOI | Multimedia Communications Community of Interest |
| MCDV | Maximum Cell Delay Variation |
| MCF | Message Communication Functions (TMN) |
| MCLR | Maximum Cell Loss Ratio |
| MCM | Multicarrier Modulation |
| MCMC | Malaysian Communications and Multimedia Commission |
| MCPC | Multiple Channel Per Carrier |
| MCPR | Multimedia Communication Processing and Representation |
| MCR | Minimum Cell Rate (ATM) |
| MCS | Master Control System |
| MCS | Multipoint Communication Service |
| MCT | Model Compatibility Test |
| MCTD | Maximum Cell Transfer Delay |
| MCU | Metered Calling Unit |
| MCU | Multipoint Control Unit |
| MCVF | Multi-Channel Voice Frequency |
| MCW | Modulated Continuous Wave |
| MD | Mediation Device |
| MDB | Management Database |
| MDBS | Mobile Database Station |
| MDF | Main Distribution Frame |
| MDIS | Mobile Data Intermediate System |
| MDN | Message Disposition Notification |
| MDN | Mobile Directory Number |
| MDNS | Managed Data Network Service |
| MDR | Memory Data Register |
| MDS | Moderate Speed Digital Subscriber Line |
| MDT | Manufacturer’s Delegated Testing |
| MDT | Mean Downtime |
| MDTRS | Mobile Digital Trunked Radio Systems |
| ME | Maintenance Entities |
| ME | Mobile Equipment |
| MEA | Modern Equivalent Asset |
| MEECN | Minimum Essential Emergency Communications Network |
| MEF | Maintenance Entity Function |
| MEG | Mobile Experts Group |
| MEO | Medium Earth Orbit |
| MEOS | Medium Earth Orbit Satellites |
| MERS | Most Economical Route Selection |
| MES | Master Earth Station |
| MExE | Mobile Station Application Execution Environment |
| MF | Mediation Function |
| MF | Medium Frequency |
| MF | Multi Frequency |
| MFD | Mode Field Diameter |
| MFLOPS | Millions of Floating Point Operations Per Second |
| MFSK | Multiple Frequency-Shift Keying |
| MG | Master Group |
| MGW | Media GateWay |
| MHF | Medium High Frequency |
| MHRP | Multi Host Routing Protocol |
| MHS | Message Handling Service |
| MHS | Message Handling Source |
| MHS | Message Handling System |
| MHz | Megahertz |
| MIB | Management Information Base |
| MIC | Management Integration Consortium |
| MIC | Medium Interface Connector |
| MIC | Microphone |
| MIC | Microwave Integrated Circuit |
| MIC | Minimum Ignition Current |
| MIC | Monolithic Integrated Circuit |
| MIC | Mutual Interface Chart |
| MICP | Mobile Internetworking Control Protocol |
| MID | Message Identifier (ATM SMDS) |
| MID | Multiplexing Identifier (ATM) |
| MIDA | Multiple Integrated Digital Access (UK) |
| MILNET | Military Network (US) |
| MIL-STD | Military Standard (US) |
| MIME | Multipurpose Internet Mail Extension |
| MIN | Mobile ID Number |
| MIP | Medium Interface Point |
| MIPS | Millions of Instructions per Second |
| MIS | Management Information Services |
| MIS | Management Information System |
| MIT | Massachusetts Institute of Technology |
| MIX | Multiservice Interchange |
| MJPEG | Multi Joint Photography Experts Group |
| MLC | Multilink Control Field (X25) |
| MLE | Maximum Likelihood Estimator |
| MLP | Multilink Protocol (X25) |
| MLPP | Multilevel Precedence And Preemption |
| MLS | Mobile Location Services |
| MLS | Multiple Listing Service |
| MMB | Milli-Metric Band (ETSI) |
| MMDS | Multichannel Multipoint Distribution System |
| MMF | MultiMode Fibre |
| MMI | Man Machine Interface |
| MMoIP | Multimedia Mail over IP |
| MMP | Multichassis Multilink PPP |
| MMS | Multimedia Message Service |
| MMSI | Maritime Mobile Service Identities |
| MNO | Mobile Network Operator |
| MNP | Mobile Number Portability |
| MO | Magneto-Optical Modem Modulator/Demodulator |
| MOC | Mobile Originating Call |
| MOCVD | Metallo-Organic Chemical Vapour Deposition |
| MOD | Demodulation |
| MOD | Model |
| MOD | Modification |
| MOD | Modulation |
| Modem | Modulator-Demodulator |
| MOH | Music on Hold |
| MOM | Method of Movements |
| MOP | Maintenance Operations Protocol |
| MOS | Mean Opinion Score (voice quality score) |
| MoU | Memorandum of Understanding |
| MOU | Minutes of Use |
| MP | Multiplexing |
| MP3 | MPEG Audio Layer 3 |
| MPC | Multi Frequency Code |
| MPEG | Motion Pictures Expert Group |
| MPF | Metallic Path Facility |
| MPLS | MultiProtocol Label Switching |
| MPOA | Multiprotocol over ATM |
| MPP | Multichannel Point-to Point Protocol |
| MPPP | Multilink Point-to-Point Protocol |
| MRA | Mutual Recognition Agreement |
| MRCF | Maximum Rate of Exchange of Frequency |
| MS | Managed Services |
| MS | Mobile Station |
| MSB | Most Significant Bit |
| MSC | Main Switching Centre |
| MSC | Mobile Switching Centre |
| MSDT | Multi-Services Distant Terminal |
| MSE | MExE Service Environment |
| MSG | Message |
| MSI | Mid-Span Interconnection |
| MSIN | Mobile Station Identification Number |
| MSISDN | Mobile Subscriber International Subscriber Identity Number |
| MSISDN | Mobile Station International ISDN |
| MSK | Minimum Shifting Key |
| MSN | Microsoft Network |
| MSO | Mobile Switching Office |
| MSO | Multiple Service Operator |
| MSP | Multiplex Section Protection |
| MSRN | Mobile Station Roaming Number |
| MSS | Mobile Satellite Systems |
| MSS | MAN Switching System |
| MSSHO | Mobile Speed Sensitive Handover |
| MS-SPRING | Multiplex Section Shared Protection Ring |
| MST | Multi-Service Terminal |
| MT | Mobile Termination |
| MTA | Mail Transport Agent |
| MTA | Message Transfer Agent |
| MTBF | Mean Time Between Failures |
| MTBM | Mean Time Between Maintenance |
| MTBO | Mean Time Between Outages |
| MTBPM | Mean Time Between Preventive Maintenance |
| MTC | Mobile Terminated Call |
| MTF | Modulation Transfer Function |
| MTP | Message Transfer Part |
| MTP | Multicast Transport Protocol |
| MTS | Message Telecommunications Service |
| MTS | Message Toll Service |
| MTS | Message Transfer System |
| MTSO | Mobile Telephone Switching Office |
| MTSR | Mean Time to Service Restoral |
| MTTR | Mean Time to Repair |
| MTU | Maximum Transmission Unit |
| MTU | Multi-Tenant Unit |
| MU | Message Unit |
| MUF | Maximum Usable Frequency |
| muldem | Multiplexer/Demultiplexer |
| MUNDI | Multiplexed Network for Distributive and Interactive Services |
| MUX | Multiplexer |
| MUXing | Multiplexing |
| MVDS | Microwave Video Distribution System |
| MVDS | Multipoint Video Distribution System |
| MVIP | Multi Vendor Integration Protocol |
| MVNO | Mobile Virtual Network Operator |
| MVPRP | Multivendor Problem Resolution Process |
| MVS | Multiple Virtual Storage |
| MWI | Message Waiting Indicator |
| MWV | Maximum Working Voltage |
| N | |
| NA | Network Adaptor |
| NA | Network Aspects |
| NA | Numerical Aperture |
| NACD | Network Automatic Call Distribution |
| NACS | NetWare Asynchronous Communication Services |
| NACSEM | National Communications Security Emanation Memorandum |
| NACSIM | National Communications Security Information Memorandum |
| NADF | North American Directory Forum |
| NADN | Nearest Active Downstream Neighbour |
| NAK | Negative Acknowledgement |
| NAM | Numeric Assignment Module |
| NAMAS | National Measurement Accreditation Service |
| N-AMPS | Narrowband Advanced Mobile Phone System |
| NANOG | North American Network Operator’s Group |
| NANP | North American Numbering Plan |
| NANPA | North American Numbering Plan Administration |
| NAP | Network Access Point (Internet) |
| NAP | Network Access Provider (US) |
| NASA | National Aeronautics and Space Administration |
| NAT | Network Address Translation |
| NATA | North American Telecommunications Allocation |
| NAU | Network Addressable Unit |
| NAUN | Nearest Active Upstream Neighbour |
| NAVSTAR-GPS | Navigational Satellite Timing and Ranging--Global Positioning System |
| NB | Notified Body |
| NBDP | Narrow Band Direct Printing |
| NBFM | Narrowband Frequency Modulation |
| NBH | Network Busy Hour |
| NBMA | NonBroadcast MultiAccess |
| NBRVF | Narrowband Radio Voice Frequency |
| NBSV | Narrowband Secure Voice |
| NC | Network Computer |
| NCA | National Communications Authority (Ghana) |
| NCC | Namibian Communications Commission |
| NCC | Nigerian Communications Commission |
| NCC | Network Control Centre |
| NCCF | Network Communication Control Facility |
| NCCN | Network Charge Change Notice |
| NCC | New Common Carrier (Japan) |
| NCO | Numerical Control Oscillator |
| NCOP | Network Code of Practice |
| NCP | Network Connection Point |
| NCP | Network Configuration Process |
| NCP | Network Control Point |
| NCP | Network Control Programme |
| NCS | National Communications System |
| NCS | Net Control Station |
| NCSC | National Communications Security Committee |
| NCTE | Network Channel Terminating Equipment |
| NDCS | Network Data Control System |
| NDIS | Network Device Interface Standard |
| NDS | Network Distribution System |
| NE | Network Element |
| NEBS | New Equipment Building Specifications |
| NECA | National Exchange Carrier Association |
| NEF | Network Element Function Block |
| NEMS | Network Element Management Server |
| NEP | Noise Equivalent Power |
| NER | Network Efficiency Ratio |
| NES | Noise Equivalent Signal |
| NET | Norme Europeenne de Telecommunications |
| NetBEUI | NetBIOS Extended User Interface |
| NetBIOS | Network Basic Input/Output System |
| NETC | National Electronics Test Centre (Ireland) |
| NETID | Network Identifier |
| NEXT | Near End Cross Talk |
| NF | Noise Figure |
| NGN | Next-Generation Network |
| NHH | National Communications Authority (Hungary) |
| NHRP | Next Hop Routing Protocol |
| NHS | Next Hop Server |
| NI | Network Interface |
| NIC | Network Information Centre (Internet Registry) |
| NIC | Network Interface Card (LAN) |
| NICC | Network Interoperability Consultative Committee |
| NICE | Network Information and Control Exchange |
| NICS | NATO Integrated Communications System |
| NID | Network Information Database |
| NID | Network Interface Device |
| NID | Network Inward Dialling |
| NII | National Information Infrastructure |
| NIOD | Network Inward/Outward Dialling |
| NIS | Network Information Service |
| N-ISDN | Narrow-band Integrated Services Digital Network (ISDN) |
| NIST | National Institute of Standards and Technology (US) |
| NIT | Networking Interworking Tests |
| NIU | Network Interface Unit |
| NIUF | North American ISDN Users Forum |
| NL | Network Layer |
| NL | Number of Unallocated Channels on Link |
| NLD | National Long Distance |
| NLDM | Network Logical Data Manager |
| NLP | National Level Programme |
| NLPID | Network Layer Protocol Identifier |
| NLSP | NetWare Link Services Protocol |
| NM | Network Management |
| NM | Network Module |
| NMC | Network Management Centre |
| NMDS | Narrow-band Multi-service Delivery System |
| NML/NMS | Network Management Layer/Network Management Service |
| NMP | Network Management Protocol |
| NMR | Nuclear Magnetic Resonance Scanner |
| NMS | Network Management System |
| NMSI | National Mobile Station Identification Number |
| NMT | Nordic Mobile Telephone System |
| NN | Network Node |
| NNG | National Number Group |
| NNI | Network Node Interface (ATM) |
| NNI | Network-to-Network Interface |
| NOA | Nature of Address |
| NOAF | Network Operator Facility |
| NOC | Network Operations Centre |
| NOCC | Network Operations Control Centre |
| NOD | Network Outward Dialling |
| NORC | Network Operators Research Committee |
| NOS | Network Operating System |
| NP | Network Performance |
| NP | Number Portability |
| NPA | Numbering Plan Area |
| NPC | Network Parameter Control (ATM) |
| NPDU | Network Layer Protocol Data Unit |
| NPI | Numbering Plan Identification |
| NPR | Noise Power Ratio |
| NPT | Norwegian Post and Telecommunications Authority |
| NRA | National Regulatory Authority |
| NREN | National Research and Education Network (US) |
| NRI | Net Radio Interface |
| NRM | Network Resource Manager |
| NRM | Normal Response Mode |
| NRZ | Non-Return-to-Zero |
| NRZ-M | Non-Return-to-Zero Mark |
| NRZ-S | Non-Return-to-Zero Space |
| NS/EP | Telecommunications National Security or Emergency Preparedness Telecommunications |
| NSA | National Security Agency (US) |
| NSAP | Network Service Access Point |
| NSAPA | Network Service Access Point Address |
| NSC | Network Service Centre |
| NSF | National Science Foundation (US) |
| NSOs | National Standards Organisations |
| NSP | Network Service Provider |
| NSP | Native Signal Processing |
| NSP | Network Service Protocol |
| NSS | Network Switching Sub-System (GSM) |
| NSS | Network Subsystem |
| NSSG | Network Solutions and Service Group |
| NSTAC | National Security Telecommunications Advisory Committee (US) |
| NT | Network Termination (ISDN) |
| NT | New Technology |
| NTA | Nepal Telecommunications Authority |
| NTC | National Telecommunications Commission (Philippines) |
| NTCN | National Telecommunications Coordinating Network |
| NTE | Network Terminating Equipment |
| NTI | Network Terminating Interface |
| NTMS | National Telecommunications Management Structure |
| NTN | Network Terminal Number |
| NTO | Network Terminal Option |
| NTP | Network Termination Point |
| NTP | Network Time Protocol |
| NTRA | National Telecommunications Regulatory Authority of Egypt |
| NTRC | National Telecommunications Regulatory Commission (St Lucia) |
| NTRC | National Telecommunications Regulatory Commission (St Vincent and the Grenadines) |
| NTS | Number Translation Services |
| NTSA | Networking Technical Support Alliance |
| NTSC | National Television Standards Committee |
| NTT | Nippon Telegraph & Telephone (Japan) |
| NTTA | Network Termination and Testing Apparatus |
| NTU | Network Termination Unit |
| NVRAM | NonVolatile RAM |
| NVT ASCII | Network Virtual Terminal ASCII Nailed Line |
| NXX | Network Numbering Exchange |
| O | |
| O&M | Operations and Maintenance |
| OA&M | Operations, Administration and Maintenance |
| OAC | Operator Assisted Calls |
| OAM&P | Operations, Administration, Maintenance and Provisioning |
| OB | Outside Broadcast |
| OBC | Out-of-Band Connection |
| OBM | Optimised Bandwidth Management |
| OC | Operations Centre |
| OC | Optical Carrier (SONET) |
| OCC | Other Common Carriers |
| OCCA | Open Cooperative Computing Architecture |
| OCHC | Operator Call Handling Centre |
| OCR | Optical Character Recognition |
| OCR | Optical Character Reader |
| OCTPR | Office of the Commissioner of Telecommunications & Postal Regulation (Cyprus) |
| OCU | Orderwire Control Unit |
| OD | Optical Density |
| ODA | Open Document Architecture |
| ODBC | Open Database Connectivity |
| ODF | Optical Distribution Frame |
| ODI | Open Data-Link Interface |
| ODIF | Open Document Interchange Format |
| ODS | Operational Data Store |
| ODSI | Open Directory Services Interface |
| OECD | Organisation for Economic Cooperation and Development |
| OEIC | Opto-Electronic Integrated Circuit |
| OEM | Original Equipment Manufacturer |
| OFC | Optical Fibre, Conductive |
| OFCOM | Office Fédéral de la Communication (Switzerland - see also BAKOM) |
| OFCOM | Office of Communications (UK) |
| OFCP | Optical Fibre, Conductive, Plenum |
| OFCR | Optical Fibre, Conductive, Riser |
| OFDM | Orthogonal Frequency Division Multiplex |
| OFM | Optical Frequency Multiplexing |
| OFN | Optical Fibre, Nonconductive |
| OFNP | Optical Fibre, Nonconductive, Plenum |
| OFNR | Optical Fibre, Nonconductive, Riser |
| OHD | On Hook Dialling |
| OID | Object Identifier |
| OIM | OSI Internet Management |
| OLAP | Online Analytical Processing |
| OLC | Optical Loop Carrier |
| OLI | Optical Line Inlet |
| OLO | Other Licensed Operator |
| OLO | Optical Line Outlet |
| OLR | Overall Loudness Rating |
| OLTE | Optical Line Terminating Equipment |
| OMA | Object Management Architecture |
| OMA | Open Mobile Alliance |
| OMC | Operations and Maintenance Centre |
| OME | Operator Mobile Exchange |
| OMERT | Office Malagasy d’Études et de Régulation des Télécommunications (Madagascar) |
| OMF | Object Management Framework |
| OMG | Object Management Group |
| OMP | Open Market Provision |
| OMT | Operations and Maintenance Terminal |
| ONA | Open Network Architecture |
| ONAL | Off-Network Access Line |
| ONC | Open Network Computing |
| ONMS | Open Network Management System |
| ONP | Open Network Provision |
| ONPCCP | ONP Consultative and Co-ordination Platform |
| ONU | Optical Network Unit |
| OOE | Organisation Outside ETSI |
| OOP | Object-Oriented Programming |
| OPEX | Operating Expanditures |
| opm | Operations Per Minute |
| OPMODEL | Operations Model |
| OPSEC | Operations Security |
| OPTA | Onafhankelijke Post en Telecommunicatie Authoriteit (NRA of the Netherlands) |
| OPX | Off Premises Extension |
| OQPSK | Orthagonal Quadrature PSK |
| OR | Off-Route Aeronautical Mobile Service |
| ORB | Object Request Broker |
| ORDR | Optical Time Domain Reflectometry |
| ORM | Optically Remote Switching Module |
| OS | Operations Systems |
| OSA | Open Service Architecture |
| OSF | Open Software Foundation |
| OSF | Operations Systems Function Block |
| OSHA | Occupational Safety and Health Administration (US) |
| OSI | Open Switching Interval |
| OSI | Open Systems Interconnection (ISO interface specifications) |
| OSI/NMF | OSI Network Management Forum |
| OSINET | OSI Network |
| OSIPTEL | Organismo Supervisor de Inversión Privada en Telecomunicaciones (Peru) |
| OSI-RM | Open Systems Interconnection--Reference Model |
| OSIRM | Open Systems Interconnection Reference Model (ISO ITU-T) |
| OSITOP | Open Systems Interconnection/Technical and Office Protocol |
| OSP | Outside Plant |
| OSPF | Open Shortest Path First |
| OSRI | Originating Stations Routing Indicator |
| OSS | One Stop Shopping |
| OSS | Operation Support Systems |
| OSSN | Originating Stations Serial Number |
| OTA | Over-the-Air |
| OTAM | Over-the-Air Management of Automated HF Network Nodes |
| OTAR | Over-the-Air Rekeying |
| OTDR | Optical Time Domain Reflectometer |
| OTE | Operator Tandem Exchange |
| OTRT | Office Tchadien de Régulation des Télécoms (Chad) |
| OUI | Organisational Unique Identifier |
| OUR | Office of Utilities Regulation (Jamaica) |
| OW | Orderwire |
| P | |
| p/a r | Peak-to-Average Ratio |
| P/P | Point-to-Point |
| P2P | Person-to-Person |
| PABX | Private Automatic Branch Exchange |
| PAC | Programme Advisory Committee (ETSI) |
| PACE | Priority Access Control Enabled |
| PACS | Personal Access Communications System |
| PACT | Public Access Cordless Telephony |
| PAD | Packet Assembler/Disassembler |
| PAL | Phase Alternation by Line (colour TV standard) |
| PAL-M | Phase Alternation by Line - Modified |
| PAM | Pulse Amplitude Modulation |
| PAMA | Pulse-Address Multiple Access |
| PAMR | Public Access Mobile Radio |
| PAMS | Perceptual Analysis / Measurement System (ITU-based standard P.800) |
| PAN | Personal Area Network |
| PAP | Password Authentication Protocol |
| PAR | Performance Analysis And Review |
| PARAMP | Parametric Amplifier |
| PAT | Port Address Translation |
| PAX | Private Automatic Exchange |
| PBER | Pseudo-Bit-Error-Ratio |
| PBP | Packet Burst Protocol |
| PBX | Private Branch Exchange |
| PC | Carrier Power (of a radio transmitter) |
| PC | Path Control |
| PC | Printed Circuit |
| PCA | Position of Closed Approach |
| PCB | Power Circuit Breaker |
| PCB | Printed Circuit Board |
| PCB | Process Control Block |
| PCB | Public Call Box (payphone) |
| PCC | Prepaid Calling Card |
| PCC | Primary Cross Connect |
| PCH | Paging Channel |
| PCI | Peripheral Component Interconnect |
| PCI | Pre-Connection Inspection |
| PCI | Programmable Communication Interface |
| PCI | Protocol Control Information |
| PCIA | Personal Communications Industry Association |
| PCM | Plug Compatible Module |
| PCM | Process Control Module |
| PCM | Pulse Code Modulation |
| PCMCIA | Personal Computer Memory Card Industry Association |
| PCN | Personal Communications Network |
| PCN | Personal Communications Number |
| PCO | Public Call Office |
| PCR | Peak Cell Rate (ATM) |
| PCS | Personal Communication Services |
| PCS | Personal Communication Space |
| PCS | Personal Communication System |
| PCS | Plastic-Clad Silica (fibre) |
| PCS | Port Concentrator Switch |
| PCS1900 | Personal Communications System 1900 MHz |
| PCSN | Private Circuit Switching Network |
| PCSR | Parallel Channels Signalling Rate |
| PCT | Private Communication Technology |
| PCU | Premises Control Unit |
| PDA | Personal Digital Assistant |
| PDC | Personal Digital Cellular |
| PDD | Post Dial Delay |
| PDE | Positioning Determination Entity |
| Portable Document Format | |
| PDH | Plesiochronous Digital Hierarchy |
| PDM | Pulse-Duration Modulation |
| PDN | Packet Data Network |
| PDN | Public Data Network |
| PDS | Power Distribution System |
| PDS | Protected Distribution System |
| PDT | Programmable Data Terminal |
| PDU | Protocol Data Unit |
| PE | Phase-Encoded |
| PE | Public Enquiry |
| PEAN | Pan-European ATM Network |
| PED | Portable Electronic Devices |
| PEM | Privacy Enhanced Mail |
| PEP | Peak Envelope Power (of a radio transmitter) |
| PESQ | Perceptual Evaluation of Speech Quality (ITU-standard P.862) |
| PET | Planning Exercise in Telecommunications technologies (forerunner of RACE) |
| PF, pf | Picofarad |
| PF | Power Factor |
| PFD | Power Flux Density |
| PFM | Pulse-Frequency Modulation |
| PGT-10 | The Conference of European Postal and Telecommunications Administrations’ general tariff principles study group. |
| PH | Personal Handyphone System |
| PHY | Physical Layer |
| PHY | Physical Sublayer |
| PI | Protection Interval |
| PI | Programming Infrastructure |
| PIC | Plastic Insulated Cable |
| PIC | Primary Interexchange Carrier (US) |
| PICS | Protocol Implementation Conformance Statement |
| PIM | Personal Information Manager |
| PIM | Protocol Independent Multicast |
| PIM DM | PIM Dense Mode |
| PIM SM | PIM Sparse Mode |
| PIN | Personal Identification Number |
| PIN | Positive-Intrinsic-Negative |
| ping | Packet Internet Groper |
| PINX | Private Telecommunications Network Exchange |
| PITCOM | Parliamentary Information Technology Committee (UK) |
| PIV | Peak Inverse Voltage |
| PIXIT | Protocol Implementation Extra Information for Testing |
| PKC | Public Key Cryptology |
| PKI | Public Key Infrastructure |
| PL | Private Line |
| PL | Project Line |
| PLAR | Private Line, Automatic Ringdown |
| PLC | Power Line Communications |
| PLC | Programming Logic Controller |
| PLCP | Physical Layer Convergence Procedure |
| PLIM | Physical Layer Interface Module |
| PLISO | Plesisochronous |
| PLL | Phase-Locked Loop |
| PLMN | Public Land Mobile Network |
| PLN | Private Line Network |
| PLP | Packet Layer Protocol (X25) |
| PLR | Pulse Link Repeater |
| PLS | Physical Signalling Sublayer |
| PLSP | PNNI Link State Packets |
| PLU | Primary Logical Unit |
| PM | Mean Power |
| PM | Phase Modulation |
| PM | Physical Medium |
| PM | Polarisation-Maintaining (optical fibre) |
| PM | Preventive Maintenance |
| PM | Pulse Modulation |
| PMA | Physical Medium Attachment |
| PMBS | Packet Mode Bearer Service |
| PMBX | Private Manual Exchange System |
| PMD | Physical Medium Dependent (FDDI) |
| PMN | Public Mobile Network |
| PMO | Programme Management Office |
| PMR | Private Mobile Radio |
| PNNI | Private Network Node Interface (ATM) |
| PNO | Public Network Operator |
| PnP | Plug-and-Play |
| PNT | Private Network Termination |
| POC | Point of Connection |
| POD | Programmable Option Devices |
| POET | Packet Over E3/T3 |
| POI | Point Of Interconnect |
| PON | Passive Optical Network |
| POP | Point of Presence |
| POP | Post Office Protocol |
| PoS | Point Of Sale |
| POSI | Promotion of OSI |
| POSIT | Profiles for Open Systems Interworking Technologies |
| POSIX | Portable Operating System Interface for Computer Environments |
| POSTEL | Directorate General of Posts and Telecommunications (Indonesia) |
| POTRAZ | Postal and Telecommunications Regulatory Authority of Zimbabwe |
| POTS | Plain Old Telephone Service |
| P-P | Peak-to-Peak |
| PP | Polarisation-Preserving (optical fibre) |
| PPC | Pay-Per-Call |
| PPCC | Prepaid Calling Card |
| PPM | Pulse-Position Modulation |
| PPP | Point-to-Point Protocol |
| PPS | Precise Positioning Service |
| PPS | Pulses per Second |
| PPV | Pay-per-View |
| PQA | Product Quality Assurance |
| PR | Pulse Rate |
| PRBS | Pseudo Random Bits Sequence |
| PRD | Programme Reference Document |
| PRF | Pulse-Repetition Frequency |
| PRI | Primary Rate Interface (ISDN) |
| PRM | Pulse-Rate Modulation |
| PRMD | Private Management Domain |
| PRN | Pseudo Random Noise |
| PROM | Programmable Read-Only Memory |
| PRP | Primary Routing Point |
| PRR | Pulse Repetition Rate |
| PRS | Premium Rate Service |
| PRSIG | Pacific Rim SMDS Interest Group |
| PRSL | Primary Area Switch Locator |
| PS | Packet Switched |
| PS | Paging Systems |
| PS | Permanent Signal |
| PS | Power Supply |
| PSB | Public Service Board |
| PSC | Public Service Commission (US) |
| PSD | Power Spectral Density |
| PSDN | Packet Switched Data Network |
| PSE | Packet Switching Exchange |
| PSK | Phase Shift Keying |
| PSN | Packet-Switched Network |
| PSN | People with Special Needs |
| PSN | Public Switched Network |
| PSP | Personal Software Products |
| PSPDN | Packet Switched Public Data Network |
| PSQM | Perceptual Speech Quality Measurement (ITU-standard P.861) |
| PST | Plug-and-Socket Terminated |
| PSTN | Public Switched Telecommunications Network |
| PSU | Power Supply Unit |
| PT | Payload Type |
| PTA | Pakistan Telecommunication Authority |
| PTA | Post and Telecom Administration (Iceland) |
| PTD | Post and Telegraph Department (Thailand) |
| PTF | Patch And Test Facility |
| PTI | Packet Type Identifier (X25) |
| PTI | Payload Type Identifier (ATM) |
| PTM | Packet Transport Mode |
| PTM | Plesiochronous Transmission |
| PTM | Pulse-Time Modulation |
| PTN | Public Telecommunication Network |
| PTNX | Private Telecommunications Network Exchange |
| PTO | Public Telecommunication Operator |
| PTS | National Post and Telecom Agency (Sweden) |
| PTS | Public Telecommunications System |
| PTT | Post, Telephone and Telegraph |
| PTT | Push-to-Talk |
| PTTC | Paper Tape Transmission Code |
| PTTI | Precise Time And Time Interval |
| PU | Pick-Up |
| PU | Power Unit |
| PU | Physical Unit |
| PUC | Public Utilities Commission (US) |
| PURA | Public Utility Regulatory Authority (Gambia) |
| PVC | Permanent Virtual Circuits |
| PVC | Polyvinyl Chloride |
| PVN | Private Virtual Network |
| PVP | Permanent Virtual Paths |
| PW | Private Wire |
| PWB | Printed Wiring Board |
| PWM | Pulse-Width Modulation |
| PWT | Personal Wireless Telephone |
| PX | Private Exchange |
| PXML | Private Exchange Master List |
| Q | |
| Q3 | Network Management Interface (ITU-T) |
| QA | Quality Assurance |
| QA | Q-Adapter (TMN) |
| QAFQ | Adapter Block (TMN) |
| QAIG | Signalling in Q-Point (private ISDN networks) |
| QAM | Quadrature Amplitude Modulation |
| Q-bit | Qualified Data Bit (X25) |
| QC | Quality Control |
| QCIF | Quarter CIF |
| QI | Quality Index |
| QLLC | Qualified Logical Link Control |
| QMR | Qualitative Material Requirement |
| QoS | Quality of Service |
| QPD | Qualified Program Document |
| QPL | Qualified Product List |
| QPSK | Quadrature Phase Shift Key |
| QPSX | Queued Packet Synchronous Exchange |
| QRC | Quick Reaction Capability |
| QRS | Quasi-Random Signal |
| QRSS | Quasi-Random Signal Sequence |
| QSIG | Unified international corporate network signalling standard |
| QSTAG | Quadripartite Standardisation Agreement |
| QUICK | Trenching Quicker Underground Integrated Cabling and Networking |
| R | |
| R | Receiver |
| R | Route Service |
| R&D | Research & Development |
| R/T | Real Time |
| RA | Remote Access |
| RAC | Relay Access Card |
| RACE | Research and Development in Advanced Communications Technologies in Europe |
| RACH | Random Access Channel |
| RADHAZ | Electromagnetic Radiation Hazards |
| RADINT | Radar Intelligence |
| RADIUS | Remote Dial-In User Service |
| RADSL | Rate Adaptive Digital Subscriber Line |
| RAIM | Receiver Autonomous Integrity |
| RAM | Random Access Memory |
| RAM | Reliability, Availability, And Maintainability |
| RAN | Radio Access Network |
| RARE | Réseaux Associés pour la Recherche Européenne |
| RARP | Reverse Address Resolution Protocol |
| RAS | Remote Access Server (Remote LAN) |
| RATT | Radio Teletypewriter System |
| RBBS | Residential Broadband Service |
| RBES | Rule-Based Expert Systems |
| RBOC | Regional Bell Operating Companies (US) |
| RC | Rate Centre |
| RC | Reflection Coefficient |
| RC | Reference Configuration |
| RC | Repeating Coil |
| RC | Resource Controller |
| RCC | Radio Common Carrier (US) |
| RCC | Reverse Control Channel |
| RCE | Remote Channel Extenders |
| RCF | Routing Control Field |
| RCO | RACE Central Office |
| RCP | Remote Copy Protocol |
| RCU | Remote Control Unit |
| RCU | Remote Concentrator Unit |
| RCVR | Receiver |
| RD | Routing Domain (ATM ISO) |
| RD&E | Research Development and Engineering |
| RD&T | Research Development and Technology |
| RDBMS | Relational Database Management System |
| RDF | Route Designator Field |
| RDI | Remote Defect Identification |
| RDP | RACE Definition |
| RDS | Radio Data Signal/System |
| RDSS | Radio Determination Satellite Service |
| RDTD | Restricted Differential Time Delay |
| RegTP | Regulierungsbehörde für Telekommunikation und Post (German NRA) |
| REM | Ring Error Monitor |
| REN | Ringer Equivalent Number |
| REP | Repeat |
| RES | Radio Equipment and Systems |
| RESP | Response |
| RET | Returning |
| RF | Radio Frequencies |
| RFA | Random Fixed Access |
| RFH | Remote Frame Handler (ISDN) |
| RFI | Radio Frequency Interference |
| RFS | Ready for Service |
| RG | Research Group |
| RG | Ring Ground |
| RH | Relative Humidity |
| RHR | Radio Horizon Range |
| RI | Routing Indicator |
| RIC | RACE Industrial Consortium |
| RIF | Routing Information Field (Source Routing) |
| RII | Routing Information Indicator (Source Routing) |
| RIM | Radio Identity Model |
| RIM | Receiver Intermodulation |
| RIM | Request Initialisation Mode (HDLC) |
| RIO | Reference Interconnection Offer |
| RIP | Routing Information Protocol |
| RISC | Reduced Instruction Set Computing |
| RISE | Retrieval and Interchange of Standards in Europe |
| RJ | Registered Jack |
| RJE | Remote Job Entry |
| RLM | Redundant Link Manager |
| RLR | Receive Loudness Rating |
| RLSD | Receive Line Signal Detector |
| RM | Resource Management |
| RMC | RACE Management Committee |
| RMON | Remote Network Monitoring |
| RMU | Resource Management Units |
| RNC | Radio Network Controller |
| RNS | Radio Network Subsystem |
| RO | Read Only / Receive Only |
| ROA | Recognised Operating Agency |
| ROC | Required Operational Capability |
| ROCE | Return on Capital Employed |
| ROH | Receiver Off-Hook |
| ROI | Return On Investment |
| ROM | Read-Only Memory |
| ROMP | Remote Operations Microprocessor |
| RoR | Rate of Return |
| ROSE | Remote Operation Service Element (Application Layer) |
| RP | Registration Point |
| RPC | Remote Procedure Call |
| RPF | Reverse Path Forwarding |
| RPI | Retail Price Index |
| RPS | Ring Parameter Server |
| RQ | Repeat-Request |
| RR | Radio Regulations (ITU) |
| RR | Register Recall (Timed Break) |
| RR | Relative Rate |
| RR | Repetition Rate |
| RRB | Radio Regulations Board |
| RS | Remote Station |
| RSA | Rivest, Shamir, and Adelman (public-key cryptographic system) |
| RSCV | Route Selection Control Vector |
| RSH | Remote Shell Protocol |
| RSL | Received Signal Level |
| RSM | Remote Switching Module |
| RSP | Route/Switch Processor |
| RSRB | Remote Source-Route Bridging |
| RSS | Radio Subsystem |
| RSS | Remote Switch Subsystem |
| RSVP | Resource Reservation Protocol |
| RT | Real Time |
| RT | Remote Terminal |
| RT | Ringback Tone |
| RT | Routing Type |
| RTA | Remote Trunk Arrangement |
| RTC/RTS | Regional Tele Centre/Regional Tele Server |
| RTCP | Real-Time Control Protocol |
| RTCP | RTP Control Protocol |
| RTF | Rich Text Format |
| RTP | Rapid Transport Protocol |
| RTP | Real-Time Transport Protocol |
| RTP | Routing Table Protocol |
| RTS | Request to Send |
| RTSC | Regional Telematic Service Centre |
| RTSE | Remote Transfer Service Element (Application Layer) |
| RTSP | Real Time Streaming Protocol |
| RTTE | Radio and Telecommunication Terminal Equipment (also R&TTE) |
| RTTE-CA | Radio and Telecommunication Terminal Equipment Compliance Association |
| RTTY | Radio Teletypewriter |
| RTU | Radio Termination Unit |
| RTU | Remote Telemetry Units |
| RTU | Right to Use |
| Rt-VBR | Real Time Variable Bit Rate |
| RTX | Request to Transmit |
| RU | Request/Response Unit |
| RUDP | Reliable User Data Protocol |
| RUO | Reference Unbundling Offer |
| RVA | Reactive Volt-Ampere |
| RVWG | Reliability and Vulnerability Working Group |
| RWI | Radio and Wire Integration |
| RWT | Right When Tested |
| RX | Receiver |
| Rx | Reception |
| RXLEV | Received Signal Level |
| RXQUAL | Received Signal Quality |
| RZ | Return-to-Zero |
| S | |
| S x S | Step-by-Step |
| S/H | Sample and Hold |
| S/N | Signal to Noise Ratio |
| S/R | Send and Receive |
| SA | Selective Availability |
| SA | Source Address |
| SA | Subscribers’ Apparatus |
| SA | Switched Access |
| SAA | Systems Application Architecture (IBM) |
| SAACH | Slow Associated Control Channel |
| SAAL | Signalling ATM Adaptation Layer (ATM) |
| SABM | Set Asynchronous Balanced Mode (HDLC) |
| SABME | Set Asynchronous Balanced Mode Extended (HDLC) |
| SAC | Service Access Code |
| SAC | Single-Attached Concentrator |
| SAC | Stand-Alone Costs |
| SAER | Service and Equipment Record |
| SAM | System Administration Module |
| SAP | Service Advertising Protocol |
| SAP | Source Access Point |
| SAPI | Service Access Point Identifier (LAPD) |
| SAR | Segmentation and Re-assembly (ATM) |
| SARM | Set Asynchronous Response Mode (HDLC) |
| SAS | Simple Attachment Scheme |
| SAS | Single Attachment Station |
| SAS | Statically Assigned Socket |
| SAT | SIM Application Toolkit |
| SATAN | System Administrator Tool for Analysing Networks |
| SB | Synchronisation Burst |
| SBSVC | Selective Broadcast Signalling Virtual Channel (B- ISDN) |
| SC | Self-Contained |
| SC | Signalling Converter |
| SC | Switching Centre |
| SC | Standards Committee (ISO) |
| SCA | System Communication Architecture |
| SCADA | Supervisory Control and Data |
| SCC | Specialised Common Carrier |
| SCCP | Signalling Connection Control Part |
| SCDC | Single Commutation Direct Current |
| SCE | Service Creation Environment |
| SCEF | Service Creation Environment Function |
| SCF | Service Control Function |
| SCH | Synchronisation Channel |
| SCP | Service Control Point |
| SCP | Session Control Protocol |
| SCPC | Single Channel per Carrier |
| SCR | Semiconductor-Controlled Rectifier |
| SCR | Silicon-Controlled Rectifier |
| SCR | Sustained Cell Rate (ATM) |
| SCRA | Small Call Routing Apparatus |
| SCSI | Small Computer Systems Interface |
| SCSR | Single Channel Signalling Rate |
| SCTE | Society of Cable Telecommunications Engineers |
| SCVF | Single Channel Voice Frequency |
| S-DAB | Satellite Digital Audio Broadcasting |
| SDCCH | Standalone Dedicated Control Channel |
| SDF | Specialised Database Functions (TMN) |
| SDH | Synchronous Digital Hierarchy (ITU-T) |
| SDK | Software Development Kit |
| SDLC | Synchronous Data Link Control |
| SDLS | Single-Line Digital Subscriber Line |
| SDM | Space Division Multiplexing |
| SDN | Software-Defined Network (AT&T) |
| SDR | Software Defined Radio |
| SDSL | Single-Line Digital Subscriber Line |
| SDSU | SMDS Data Service Unit |
| SDU | Service Data Unit |
| SE | Support Entity |
| SE | Support Equipment |
| SECAM | Séquentiel à Mémoire (French colour TV standard) |
| SECORD | Secure Voice Cord Board |
| SECTEL | Secure Telephone |
| SEF | Support Entity Function |
| SEMKO | Swedish Institute for Testing and Approval of Electrical Equipment |
| SES | Satellite Earth Stations |
| SET | Secure Electronic Transaction |
| SETAMS | Systems Engineering, Technical Assistance, and Management Services |
| SEVAS | Secure Voice Access System |
| SEWG | Spectrum Engineering Working Group of CEPT ERC |
| S-F | Store-and-Forward |
| SF | Single-Frequency |
| SF | Super Frame |
| SFS | Single-Frequency Signalling |
| SFS | Start of Frame Sequence (LAN) |
| SG | Study Group (ITU-T) |
| SG | Supergroup |
| SGCP | Simple Gateway Control Protocol |
| SGDF | Supergroup Distribution Frame |
| SGML | Standard Generalised Markup Language |
| SGMP | Simple Gateway Monitoring Protocol |
| SGNT | Special Grade Network Trunk |
| SGSN | Serving GPRS Support Node |
| SHARES | Shared Resources HF Radio Programme |
| SHF | Super High Frequency |
| S-HTTP | Service Hypertext Transport Protocol |
| SI | International System of Units |
| SI | Statutory Instrument (Ireland and UK) |
| SIB | Service Independent Building Block |
| SID | Sudden Ionospheric Disturbance |
| SID | System ID Number |
| SIF | Signalling Information Field |
| SIG | SMD Interest Group |
| SIG | Special Interest Group |
| SIGET | Superintendencia General de Electricidad y Telecomunicaciones (El Salvador) |
| SIM | Subscriber Identity Module |
| SIMD | Single Instruction Stream Multiple Data Stream |
| SINAD | Signal-Plus-Noise-Plus-Distortion to Noise-Plus- Distortion Ratio |
| SIN | Suppliers Information Notes (British Telecom) |
| SIO | Scientific and Industrial Organisations (ITU-T) |
| SIP | Session Initiation Protocol (IETF) |
| SIP | SMDS Interface Protocol |
| SIR | Sustained Information Rate (SMDS) |
| SIT | Superintendencia de Telecomunicaciones (Guatemala) |
| SITTEL | Superintendencia de Telecomunicaciones (Bolivia) |
| SITA | Society of International Aeronautical Telecommunications |
| SITS | Special Investigation Test Schedule (UK) |
| SJF | Shortest Job First |
| SKU | Stock-Keeping Unit |
| SLA | Service Level Agreement |
| SLC | Subscriber Loop Carrier |
| SLEE | Service Logic Execution Environment |
| SLI | Service Logic Interpreter |
| SLIC | Subscriber Loop Interface Circuit |
| SLIP | Serial Line Internet Protocol (IETF) |
| SLM | Service Level Management |
| SLP | Service Logic Program |
| SLR | Send Loudness Rating |
| SLSA | Single Line Switching Apparatus |
| SLU | Sub-Loop Unbundling |
| SLUO | Sub-Loop Unbundling Operator |
| SMA | Service Management Architecture |
| SMAF | Service Management Agent Function (TMN) |
| SMAP | System Management Application Part |
| SMART | Strategy for Mobile Advanced Radio Telecommunications (initiative of DG XIII/D) |
| SMATV | Satellite Master Antenna Television |
| SMB | Server Message Block |
| SMDR | Station Message Detail Recording |
| SMDS | Switched Multimegabit Data Service (Bellcore) |
| SME | Small and Medium Size Business Enterprise |
| SMF | Service Management Function (TMN) |
| SMG | Special Mobile Group |
| SMG | Supermastergroup |
| SMI | Structure of Management Information |
| SMIP | Strategic Management Information Plan |
| SML/SMS | Service Management Layer/Service Management Service |
| SMP | Significant Market Power |
| SMP | Simple Management Protocol |
| SMP | Switching Module Processor |
| SMP | Symmetric Multiprocessing |
| SMR | Specialised Mobile Radio |
| SMRP | Simple Multicast Routing Protocol |
| SMS | Satellite Multiservice System |
| SMS | Service Management System |
| SMS | Short Message Service |
| SMSC | Short Message Service Centre |
| SMT | Station Management |
| SMT | Surface Mounting Technology |
| SMTA | Single-Line Multi-Extension Telephone Apparatus |
| SMTP | Simple Mail Transfer Protocol |
| SN | Sequence Number (ATM) |
| SN | Service Node |
| SN | Station Number |
| SN | Subscriber Number |
| SN | Switching Network |
| SNA | Special Network Access |
| SNA | Systems Network Architecture (IBM) |
| SNAP | Subnetwork Access Protocol |
| SNCP | Sub-Network Connection Protection |
| SNG | Satellite News Gathering |
| SNI | Subscriber Network Interface (SMDS) |
| SNMP | Simple Network Management Protocol |
| SNP | Sequence Number Packet (NetWare) |
| SNP | Sequence Number Protection |
| SNPA | Subnetwork Point of Attachment |
| SNR | Signal to Noise Ratio |
| SNRM | Set Normal Response Mode (HDLC) |
| SNRME | Set Normal Response Mode Extended (HDLC) |
| SO | Switching Office |
| SOGIT/SOG- ITS | Senior Officials Group for Information Technology Standards |
| SOGT | Senior Officials Group for Telecommunications |
| SOM | Start of Message |
| Sonar | Sound Navigation and Ranging |
| SONET | Synchronous Optical Network |
| SOP | Standard Operating Procedure |
| SOR | Start of Record |
| SOW | Statement of Work |
| SP | Service Provider |
| SP | Signalling Point |
| SPAG | Standards Promotion and Application Group |
| SPARC | Scalable Performance Architecture |
| SPCS | Satellite Personal Communication Services |
| SPDU | Session Protocol Data Unit |
| SPF | Shortest Path First |
| SPID | Service Profile Identifier (ISDN) |
| SPM | Space Switch Module |
| SPM | Subscriber Private Meter |
| SPOC | Single Point of Contact |
| SPP | Sequenced Packet Protocol |
| SPRK | Public Utilities Commission (Latvia) |
| SPS | Signalling Protocols and Switching |
| SPS | Standard Postioning Service |
| SPTN | Single Protocol Transport Network |
| SQE | Signal Quality Error |
| SQL | Structured Query Language |
| SR/TLB | Source-Route Translational Bridging |
| SRAM | Static Random Access Memory (RAM) |
| SRB | Source-Route Bridging |
| SREJ | Selective Reject (HDLC) |
| SRF | Specialised Resources Function (TMN) |
| SRI | SIP Relay Interface (SMDS) |
| SRIC | Short Run Incremental Costing |
| SRNC | Serving Radio Network Controller |
| SRP | Specialised Resource Point (IN) |
| SRT | Source-Route Transparent Bridging |
| SRT | Source Routing Transparent |
| SRTP | Sequenced Routing Table Protocol |
| SRTS | Synchronous Residual Time Stamp |
| SRTT | Satellite Radio Transmission Technologies |
| SS | Spread Spectrum |
| SS | Switching System |
| SS | Supplementary Service |
| SS6 | Signalling System No. 6 |
| SS7 | Signalling System No. 7 |
| SSAP | Source Service Access Point |
| SSB | Service Selection Barring |
| SSB | Single Side Band |
| SSBSC | Single Sideband Suppressed Carrier |
| SSF | Service Switching Function |
| SSH | Secure Shell Encryption |
| SSL | Signal Station Location |
| SSM | Single Segment Message (DQDB SMDS) |
| SSN | Station Serial Number |
| SSP | Service Switching Point |
| SSP | Switch-to-Switch Protocol |
| SSR | Solid-State Relay |
| SSS | Subscriber Switching Subsystem |
| SSSO | Specialised Satellite Services Operator |
| SST | Spread Spectrum Technology |
| SST | Synchronous Service Transport |
| SSUPS | Solid-State Uninterruptible Power System |
| ST | Signalling Terminal |
| STAG | Security Techniques Advisory Group (ETSI) |
| STAX | Standardisation Reference Database |
| STBX | Set Top Box |
| STD | Subscriber Trunk Dialling |
| STD | Synchronous Time Division |
| STDM | Statistical Time Division Multiplexing |
| STE | Signalling Terminal Equipment |
| STE | Spanning-Tree Explorer (LAN) |
| STEM | Strategic Telecommunication Evaluation Model |
| STFS | Standard Time and Frequency Signal |
| STL | Standard Telegraph Level |
| STL | Studio-to-Transmitter Link |
| STM | Synchronous Transfer Mode |
| STM | Synchronous Transport Module (SDH) |
| STMR | Sidetone Masked Loudness Rating |
| STP | Shielded Twisted-Pair |
| STP | Signalling Transfer Point |
| STP | Standard Temperature and Pressure |
| STS | Synchronous Transport Signal (SONET) |
| STU | Secure Telephone Unit |
| STX | Start of Transmission |
| SUBT | Subscriber Terminal |
| SUBTEL | Subsecretaría de Telecomunicaciones (Chile) |
| SVC | Signalling Virtual Channel (ATM) |
| SVC | Switched Virtual Circuit (Packet Switching) |
| SW | Software |
| SWG | Standard Wire Gauge |
| SWR | Standing Wave Ratio |
| SX | Simplex Signalling |
| SXS | Step-by-Step Switching System |
| SYNTRAN | Synchronous Transmission |
| SYSGEN | System Generation |
| T | |
| TA | Terminal Adapter (ISDN) |
| TABS | Telemetry Asynchronous Block Serial |
| TAC | Terminal Access Controller |
| TACACS | Terminal Access Controller Access Control System |
| TACS | Total Access Communications Systems |
| TADIL | Tactical Data Information Link |
| TADS | Teletypewriter Automatic Dispatch System |
| TADSS | Tactical Automatic Digital Switching System |
| TAG | Technical Advisory Group |
| TAM | Telecommunications Authority of Maldives |
| TAP | Transfer Account Procedure |
| TAP | Transmission Access Point |
| TAPI | Telephony API |
| TARM | Telephone Answering and Recording Machine |
| TAS | Suriname Telecommunications Authority |
| TASI | Time Assigned Speech Interpolation |
| TAT | Trans-Atlantic Telecommunication (cable) |
| TAXI 4B/5B | Transparent Asynchronous Transmitter/Receiver Interface 4-byte/5-byte |
| TB | Technical Body (ETSI) |
| TB | Time Break |
| TB | Transparent Bridging |
| TBB | Trans-National Broadband Backbone |
| Tbps | Terabit Per Second |
| TBR | Technical Basis for Regulation (ETSI) |
| TBR | Time Break Recall |
| TC | Toll Centre |
| TC | Transmission Control |
| TC | Transmission Convergence |
| TC | Transport Connection |
| TCA | Time of Closest Approach |
| TCAM | Telecommunications Access Method (SNA) |
| TCAP | Transaction Capabilities Application Part |
| T-Carrier | Trunk Carrier |
| TCC | Telecommunications Centre |
| TCC | Terminating Call Control |
| TCCF | Tactical Communications Control Facility |
| TCF | Technical Construction File (EU R&TTE) |
| TCF | Technical Control Facility |
| TCH | Traffic Channel |
| TCIF | Telecommunications Industry Forum |
| TCL | Interface Tool Command Line Interface |
| TCM | Time Compression Multiplexing |
| TCP | Transport Control Protocol |
| TCP/IP | Transmission Control Protocol /Internet Protocol (IETF) |
| TCRA | Tanzania Communications Regulatory Authority |
| TCRL | Test Case Reference List |
| TCS | Trusted Computer System |
| TCU | Telecommunications Control Unit (SNA) |
| TCU | Trunk Coupling Unit |
| TCVXO | Temperature Compensated-Voltage Controlled Crystal Oscillator |
| TCXO | Temperature Controlled Crystal Oscillator |
| TD | Time Delay |
| TD | Transmitter Distributor |
| T-DAB | Terrestrial Digital Audio Broadcasting |
| TD-CDMA | Time Division Code Division Multiple Access |
| TDD | Telecommunications Device for the Deaf |
| TDD | Time Division Duplexing |
| TDF | Time Division Filtering |
| TDM | Time Division Multiplexing |
| TDMA | Time Division Multiple Access |
| TDMS | Time Division Multiplex System |
| TDMS | Transmission Distortion Measuring Set |
| TDOA | Time Difference of Arrival |
| TDR | Time Domain Reflectometer |
| TDRSS | Tracking and Relay Satellite System |
| TDS | Time Division Switching |
| TD-SCDMA | Time Division Synchronised CDMA |
| TE | Techno-Economic Evaluation |
| TE | Terminal Equipment |
| TE1 | Terminal Equipment Type 1 (ISDN capable) |
| TE2 | Terminal Equipment Type 2 (non-ISDN) |
| TE&DA | Techno-Economic Evaluation & Demand Analysis |
| TEAM | Techno-Economic Ad Hoc Meeting |
| TED | Trunk Encryption Device |
| TEDIS | Trade Electronic Data Interchange Systems |
| TEHO | Tail End Hop Off |
| TEI | Terminal Endpoint Identifier (LAPD) |
| TEK | Traffic Encryption Key |
| TELCO | Telecommunications Company |
| TELCOR | Instituto Nicaraguense de Telecomunicaciones y Correos (Nicaragua) |
| TELRIC | Total Element Long Run Incremental Costs |
| TEM | Transverse Electric And Magnetic |
| TEMA | Telecommunications Equipment Manufacturers Association |
| TeMIP | Telecommunications Management Information Platform (Compaq) |
| TEMPEST | Compromising Emanations |
| TEMS | Telecommunications Management System |
| TERENA | Trans-European Research and Education Networking Association |
| TeT | Techno-Economic Oriented Tools |
| TETRA | Trans European Trunked Radio |
| TFT | Thin-Film Transistor |
| TFTP | Trivial File Transfer Protocol |
| TFTS | Terrestrial Flight Telephone System |
| TG | Trunk Group |
| TGM | Trunk Group Multiplexer |
| THD | Total Harmonic Distortion |
| THF | Tremendously High Frequency |
| THL | Trans Hybrid Loss |
| THz | Terahertz |
| TI | Telecom Instruction |
| TIA | Telecommunications Industry Association (UK) |
| TIBS | Telecommunication Input Billing System (UK) |
| TIC | Token Ring Interface Coupler |
| TID | Terminal Identifier |
| TIE | Time Interval Error |
| TIFF | Tag Image File Format |
| TIG | Terminal Interoperability Group |
| TIM | Transmitter Intermodulation |
| TINA | Telecommunications Information Networking Architecture |
| TIOS | Transpath Input and Output Subsystem |
| TIP | Terminal Interface Processor |
| TIPHON | Telecommunications & Internet Protocol Harmonisation Over Networks |
| TIRKS | Trunk Information Record Keeping System (US) |
| TIS | Technical Information Sheets |
| TJF | Test Jack Frame |
| TK | Response Timer |
| TKK | Telekom-Control-Kommission (Austria) |
| TL | Transmission Level |
| TLH | Transport Layer Header |
| TLP | Transmission Level Point |
| TLP | Transmission Level Point |
| TLS | Transparent LAN Service |
| TLS | Transport Layer Security (IETF) |
| TM | Terminal Multiplexer |
| TM | Transmission and Multiplexing |
| TMA | Telecommunication Managers Association (UK) |
| TMF | Telecommunications Management Forum |
| TMN | Telecommunications Management Network |
| TMRS | Traffic Measurement and Recording Systems |
| TMS | Time-Multiplexed Switch |
| TMS | Transport Management System |
| TMSI | Temporary Mobile Subsciber Identity |
| TO | Tandem Office |
| TO | Telecommunications Operator |
| TO | Toll Office |
| TOA | Time of Arrival |
| TOC | Turn of Cycle |
| TOP | Technical Office Protocol |
| TOPS | Traffic Operator Position System |
| ToR | Terms of Reference |
| TOS | Temporarily Out of Service |
| ToS | Type of Service |
| TP | Toll Plant or Point |
| TP | Transaction Processing |
| TP | Transport Protocol (ISO) |
| TP | Twisted Pair |
| TPAU | Twisted Pair Attachment Unit |
| TPDU | Transport Protocol Data Unit |
| TPMR | Trunk Private Mobile Radio |
| TPON | Telephony over Passive Optical Network |
| TQM | Total Quality Management |
| TR | Token Ring |
| TR | Toll Restriction |
| TR | Transmit-Receive |
| TR VLAN | Token Ring Virtual LAN |
| TRA | Telecommunications Regulatory Authority (Bahrain) |
| TRA | Telecommunications Regulatory Authority (Oman) |
| TRA | Traffic Routing Administration |
| TRAI | Telecom Regulatory Authority of India |
| TRAC | Technical Recommendations Application Committee |
| TRANSEC | Transmission Security |
| TRAPI | Transport API |
| TRAU | Transcoder and Rate Adaption Unit |
| TRC | Telecommunications Regulatory Commission (Jordan) |
| TRC | Telecommunications Regulatory Commission of Sri Lanka |
| TRC | Transverse Redundancy Check |
| TRE | Telecommunications Regulatory Entity (Albania) |
| TRISL | Token Ring Inter-Switch Link |
| TRS | Telecommunications Relay Services |
| TRX | Transceiver |
| TS | Traffic Station |
| TS | Transmission Speed |
| TSAP | Transport Service Access Point |
| TSAPI | Telephony Services Applications Programming Interface |
| TSC | Transit Switching Centre |
| TSF | Telephone Service Factor |
| TSI | Time Slot Interchange |
| TSI | Transmitting Subscriber Information |
| TSK | Transmission Security Key |
| TSLRIC | Total Service Long Run Incremental Costs |
| TSM | Time Switch Module |
| TSP | Tag-Switched Path |
| TSP | Telecommunications Service Priority |
| TSPS | Traffic Service Position System |
| TSR | Telecommunications Service Request |
| TSR | Terminate and Stay Resident |
| TSRM | Telecommunication Standards Reference Manual |
| TSS | Tandem Switching System |
| TSS | Telecommunication Standardization Sector (ITU-T) |
| TSS | Telecommunications Terminal Equipment |
| TT | Dial Repeating Tie Line/Dial Repeating Tie Trunk |
| TT | Touch-Tone Adaptor |
| TT | Trunk Type |
| TTL | Transistor-Transistor Logic |
| TTL | Time-to-Live |
| TTP | Trail Termination Point (TMN) |
| TTPS | Trusted Third-Party Services |
| TTTEL | Trinidad and Tobago Telecommunications Authority |
| TRF | Tuned Radio Frequency |
| TTTN | Tandem Tie Trunk Network |
| TTY | TeleType |
| TTY | Telecommunications Device for the Deaf |
| TU | Tributary Unit |
| TUA | Telecommunications Users Association (UK) |
| TUD | Trunk Up-Down |
| TUG | Telecommunication User Group |
| TULIP | TCP and UDP over Lightweight IP |
| TUNIP | TCP and UDP over Nonexistent IP |
| TUR | Trunk Utilisation Report |
| TVR | Teletel Vitesse Rapide |
| TW | Travelling Wave |
| TWA | Two-Way Alternate (HDLC) |
| TWS | Two-way Simultaneous (HDLC) |
| TWT | Travelling Wave Tube |
| TWTA | Travelling Wave Tube Amplifier |
| TWX | Teletypewriter |
| TWX | Teletypewriter Exchange (Telex) |
| TX | Transmitter |
| TXD | Telephone Exchange Digital |
| TXE | Telephone Exchange Electronic |
| TXK | Telephone Exchange Crossbar |
| TXMTR | Transmitter |
| TXS | Telephone Exchange Strowger |
| U | |
| U/L | Uplink |
| UA | Unbalanced Asynchronous (HDLC) |
| UA | Universal Access |
| UA | Unnumbered Acknowledgement (HDLC) |
| UA | User Agent |
| UAN | User Access Node |
| UART | Universal Asynchronous Receiver Transmitter |
| UAS | Unavailable Seconds |
| UAWG | Universal ADSL Working Group |
| UAX | Unit Automatic Exchange |
| UBR | Unspecified Bit Rate (ATM) |
| UC | Unified Communications |
| UCA | Utility Communications Architecture |
| UCC | Uganda Communications Commission |
| UCD | Uniform Call Distribution |
| UCM | Universal Call Model |
| UCP | Universal Computer Protocol |
| UCS | Universal Communications Standards |
| UCSP | Unified Communications Service Provider |
| UDI | Unrestricted Digital Information (ISDN) |
| UDLP | UniDirectional Link Protocol |
| UDP | User Datagram Protocol |
| UDP | User Datagram Protocol |
| UDSL | Unidirectional HDSL |
| UE | User Equipment |
| UHF | Ultra High Frequency |
| UI | Unnumbered Information (HDLC) |
| UISG | Utility Industry Standards Group |
| UITS | Unacknowledged Information Transfer Service (ITU-T) |
| UKAS | United Kingdom Accreditation Service |
| UKIUF | UK ISDN User Forum |
| UKPOA | UK Paging Operators’ Association |
| ULF | Ultra Low Frequency |
| ULL | Unbundling the Local Loop |
| ULP | Upper-Layer Protocol |
| UM | Unified Messaging |
| Um | GSM Air Interface |
| UMB | Upper Memory Block |
| UMS | Universal Messaging System |
| UMTS | Universal Mobile Telecommunications System |
| UN | Unbalanced Normal |
| UNI | User/Network Interface |
| UNITE | User Network for Information Exchange on Telecommunications in Europe |
| UNMA | Unified Network Management Architecture |
| UP | Unnumbered Poll |
| UPC | Usage Parameter Control (ATM) |
| UPCS | Universal Personal Communications Services |
| UPF | UnPlugFests |
| UPS | Uninterruptable Power Supply |
| UPT | Universal Personal Telecommunications |
| UPTAA | UPT Access Address |
| UPTAC | UPT Access Code |
| URL | Uniform Resource Locator |
| URM | Usage Reference Model |
| URSEC | Unidad Reguladora de Servicios de Comunicaciones (Uruguay) |
| URTiP | Office of Telecommunications and Post Regulation (Poland) |
| US | Universal Service |
| USART | Universal Synchronous Asynchronous Receiver Transmitter |
| USAT | Ultra Small Aperture Terminal |
| USB | Upper Sideband |
| USC | Universal Service Contribution |
| USIM | Universal Subscriber Identity Module |
| USIM | UMTS Subscriber Identity Module |
| USO | Universal Service Obligation |
| USOC | Universal Service Order Code |
| USP | Universal Service Provider |
| USSD | Unstructured Supplementary Service Data |
| USTA | United States Telephone Association |
| UT | Universal Time |
| UTC | Coordinated Universal Time |
| UTP | Unshielded Twisted Pair |
| UTRA | Universal Terrestrial Radio Access |
| UTRAN | Universal Terrestrial Radio Access Network |
| UUI | User-to-User Indentification |
| UUS | User to User Signalling |
| uv | Ultraviolet |
| UVM | Universal Voice Module |
| UVM-C | Universal Voice Module-Channelised |
| UVM-U | Universal Voice Module-Unchannelised |
| UWB | Ultra-Wideband |
| V | |
| V/D | Voice/Data |
| V/FoIP | Voice and Fax over Internet Protocol |
| VA | Value-Added |
| VAD | Voice Activity Detection |
| VADS | Value Added Data Services |
| VADSL | Very High Speed ADSL (see VDSL) |
| VAN | Value-Added Network |
| VANS | Value Added Network Services |
| VAP | Value Added Process |
| VAR | Value-Added Reseller |
| VAS | Value Added Services |
| VB | Virtual Bandwidth |
| VBI | Vertical Blanking Intervals |
| VBNS | Very High Speed Backbone Network Service |
| VBR | Variable Bit Rate (ATM) |
| VBR-NRT | Variable Bit Rate-Non-Real-Time (ATM) |
| VBR-RT | Variable Bit Rate-Real-Time (ATM) |
| VC | Virtual Channel (ATM) |
| VC | Virtual Circuit (PSN) |
| VC | Virtual Container (SDH) |
| VCA | Voice Connecting Arrangement |
| VCC | Virtual Calling Card |
| VCC | Virtual Channel Connection (ATM) |
| VCD | Virtual Circuit Descriptor |
| VCI | Virtual Channel Identifier |
| VCI | Virtual Circuit Identifier (ATM) |
| VCL | Virtual Channel Link |
| VCS | Virtual Circuit Switch |
| VDSL | Very High-Speed Digital Subscriber Line |
| VDT | Visual Display Terminal |
| VDU | Visual Display Unit |
| VF | Variance Factor |
| VF | Voice Frequency |
| VFCT / VFCTG Voice Frequency Carrier Telegraph | |
| VFDF | Voice Frequency Distribution Frame |
| VFO | Variable-Frequency Oscillator |
| VFTG | Voice-Frequency Telegraph |
| VG | Voice Grade |
| VGA | Video Graphics Adapter |
| VGF | Voice Grade Facility |
| VHDSL | Very High Bit Rate Digital Subscriber Line |
| VHE | Virtual Home Environment |
| VHF | Very High Frequency |
| VI | Vector Identifier |
| VIP | VINES Internet Protocol |
| VL | Vector Length |
| VLAN | Virtual LAN |
| VLBR | Very Low Bit Rate |
| VLF | Very Low Frequency |
| VLI | Virtual LAN Internetwork |
| VLSI | Very Large Scale Integration |
| VLSM | Variable-Length Subnet Mask |
| VM | Virtual Machine |
| VM | Virtual Memory |
| VMAC | Virtual Media Access Control |
| VMS | Voice Messaging System |
| VMSC | Voice Mail System Centre |
| VNL | Via Net Loss |
| VNLF | Via Net Loss Factor |
| VNS | Vehicle Navigation System |
| VNS | Virtual Network Service |
| VoATM | Voice Over ATM |
| vocoder | Voice-Coder |
| VoD | Video-on-Demand |
| vodas | Voice-Operated Device Anti-Sing |
| VoFR | Voice-over-Frame Relay |
| vogad | Voice-Operated Gain-Adjusting Device |
| VoHDLC | Voice over HDLC |
| VoIP | Voice over Internet Protocol |
| Volcas | Voice-Operated Loss Control And Echo/Signalling Suppression |
| Vox | Voice-Operated Relay Circuit |
| VP | Virtual Path |
| VPC | Virtual Path Connection |
| VPDN | Virtual Private Data Network |
| VPDN | Virtual Private Dial-up Network |
| VPI | Virtual Path Identifier |
| VPL | Virtual Path Link |
| VPLMN | Visited Public Land Mobile Netwok |
| VPN | Virtual Private Networks |
| VPT | Village Public Telephone |
| VQA | Voice Quality Assessment |
| VQT | Voice Quality Testing |
| VRC | Vertical Redundancy Check |
| VRML | Virtual Reality Markup Language |
| VRRP | Virtual Router Redundancy Protocol |
| VSA | Vector Signal Analyser |
| VSAM | Virtual Storage Access Method |
| VSAT | Very Small Aperture Terminal |
| VSB | Vestigial Sideband |
| VSI | Virtual Switch Interface |
| VSM | Vestigial Sideband Modulation |
| VSWR | Voltage Standing Wave Ratio |
| VT | Virtual Terminal (ISO) |
| VT | Virtual Tributary |
| VTAM | Virtual Telecommunications Access Method |
| VTE | Virtual Terminal Environment |
| VTOA | Voice and Telephony Over ATM |
| VTP | Virtual Terminal Protocol |
| VTU | Video Teleconferencing Unit |
| VU | Unit of Volume |
| W | |
| W3C | World Wide Web Consortium |
| WAC | Wide Area Communication |
| WACS | Wireless Access Communications System |
| WADS | Wide Area Data Service |
| WAE | Wireless Application Environment |
| WAIS | Wide Area Information Services |
| WAN | Wide Area Network |
| WAP | Wireless Application Protcol |
| WARC | World Administration Radio Conference |
| WATS | Wide Area Telecommunications Service |
| WB/BB | Wide Band/Broadband |
| WBDTS | Wide Band Data Transmission Forum |
| WC | Wire Centre |
| WCDMA | Wideband CDMA |
| WCS | Wireless Communications Service |
| W-DCS | Wideband Digital Crossconnect System |
| WDM | Wavelength Division Multiplex |
| WDP | Wireless Datagram Protocol |
| WFQ | Weighted Fair Queuing |
| WG | Working Group |
| WGS | Worldwide Geodesic System |
| WiFi/WiMAX | Broadband wireless data technologies used for interconnecting computer equipment |
| WIN | Wireless In-Building Network |
| WIN | Wireless Intelligent Network |
| Winsock | Windows Socket API |
| WLAN | Wireless Local Area Network |
| WLL | Wireless Local Loop |
| WLS | Wireless Location Services (SignalSoft) |
| WM | Wireless Manager |
| WML | Wireless Markup Language |
| WP | Workpackage |
| WPBX | Wireless Private Branch Exchange |
| WPT | Wideband Packet Technology |
| WRC | World Radiocommunication Conference |
| WS | Workstation |
| WSF | Work Station Function Block |
| WSP | Wireless Session Protocol |
| WT | Wireless Transceiver |
| WTA | Wireless Telephony Application |
| WTLS | Wireless Transport Layer Security |
| WTO | World Trade Organisation |
| WTP | Wireless Transaction Protocol |
| wv | Working Voltage |
| WVDC | Working Voltage Direct Current |
| WWAN | Wireless Wide Area Network |
| WWDSA | Worldwide Digital System Architecture |
| WWW | World Wide Web |
| WWW3 | World Wide Web Consortium |
| X, Y and Z | |
| XA | Exchange Access (SMDS) |
| X-Bar | Crossbar Telephone Exchange |
| XC | Cross-Connect |
| xcvr | Receiver |
| XDF | Extended Distance Feature |
| xDSL | Generic Term for Digital Subscriber Line |
| xfmr | Transformer |
| XID | Exchange Identification (HDLC) |
| xistor, xstr | Transistor |
| XMIT | Transmit |
| XML | Extensible Markup Language |
| XMS | Extended Memory Specification |
| XMSN | Transmission |
| XMTD | Transmitted |
| XMTR | Transmitter |
| XNS | Xerox Network Systems |
| XOFF | Transmitter Off |
| XON | Transmitter On |
| XPD | Cross Polarisation Decoupling |
| XSM r | X Session Manage |
| XT | Crosstalk |
| XTagATM | Extended Tag ATM |
| Y2K | Year 2000 |
| ZBTSI | Zero Byte Times Slot Interchange |
| ZCS | Zero Code Suppression |
| ZD | Zero Defects |
| ZIP | Zone Improvement Programme (US geographic codes) |
| ZIS | Zone Information Socket |
| ZIT | Zone Information Table |
| ZLE | Zero Latency Enterprise (Compaq) |
| ZNIIS | Central Research Telecommunication Institute - Russia |
| Zo | Characteristic Impedance |
| ZST | Zone Standard Time |
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