Appendix 4 - Acronyms


The telecommunications industry delights in the use of acronyms, some of which are universally accepted, but many are specific to a particular corporation. Some acronyms may have several meanings, which can only be deciphered by the context.

                      2B1Q        2 Binary 1 Quaternary

                       4B3T        4 Binary 3 Ternary

                     4WTS        4 Wire Terminating Set

                       AAL        ATM Adaptation Layer

                      ABM        Access Bandwidth Manager; Asynchronous Balance Mode [HDLC]

                       ACD        Automatic Call Distributor

                        ACF        Access Control Field [DQDB]

                       ACK        ACKnowledgement

                      ADM        Add Drop Multiplexer

                 ADPCM        Adaptive Differential Pulse Code Modulation

                         AIS        Alarm Indication Signal

                       AMI        Automatic Mark Inversion

                    AMPS        Advanced Mobile Phone Service

                        ANI        Automatic Number Identification

                       ANS        American National Standard

                      ANSI        American National Standards Institute

                     APPN        Advanced Peer-to-Peer Networking

                        APS        Automatic Protection Switching

                   ARDIS        Advanced Radio Data Information Service

                        ARP        Address Resolution Protocol

            ARPANET        Advanced Research Projects NETwork

                       ARQ        Automatic Repeat reQuest

                     ASCII        American Standard Code for Information Interchange

                      ATM        Asynchronous Transfer Mode

                    AT&T        American Telephone & Telegraph

                        AUI        Attachment Unit Interface [Ethernet 802.3]


              BATMOS        Bipolar Analog Telecom Metal Oxide Semiconductor

                  Bellcore        BELL COmmunications REsearch

                        BCD        Binary Coded Decimal

                        BCR        Bell Communications Research

                        BER        Bit Error Ratio/Rate

                    BHCA        Busy Hour Call Attempts

                          BIP        Bit Interleaved Parity; Breaker Interface Panel

                  B-ISDN        Broadband ISDN

                      B-NT        Broadband Network Terminator

                      BnZS        Binary n Zero Substitution [n = 3, 6, or 8]

                        BOC        Bell Operating Company

                      BOM        Beginning Of Message [DQDB]

             BORSCHT        Battery, Over voltage protection, Ringing, Supervision, Coding, Hybrid, Test

                         bps        bits per second

                       BRA        Basic Rate Access (2B+D, 144 Kbps)

                         BRI        Basic Rate Interface [ISDN]

                        BSC        Binary Synchronous Communications

                           BT        British Telecom

                      B-TA        Broadband Terminal Adapter [ATM]

                       B-Te        Broadband Terminal Equipment [ATM]


            CAD/CAM        Computer Aided Design/Computer Aided Manufacturing

                         CAI        Common Air Interface

                        CAP        Competitive Access Provider

                     CBDS        Connectionless Broadband Data Service

                           CC        Central Control

                       CCIR        Consultative Committee for International Radio

                    CCITT        Comité Consultatif Internationale de Telegraphiqué et Telephoniqué

                        CCS        Common Channel Signaling

                        CCS        C [hundred] Call Seconds

                          CD        collision detection; count down [DQDB]

                   CDMA        Code Division Multiple Access

                     CDPD        Cellular Digital Packet Data

                        CDS        Copper Distribution Shelf

                        CEC        Commission of European Communities

                      CEPT        Conference on European Post & Telegraph

                         CIR        Committed Information Rate [frame relay]

                           CL        ConnectionLess

                   CLASS        Custom Local Area Signaling Services

                      CLNS        ConnectionLess Network Services [OSI]

                      CLSF        ConnectionLess Server Function [ITU-T]

                        CMI        Coded Mark Inversion

                      CMIP        Common Management Interface Protocol [ISO]

                      CMIS        Common Management Information Service [ISO]

                       CMS        Call Management Services

                          CO        Central Office

                  CODEC        COder DECoder

                      COM        Continuation Of Message

           COMPAND        COMpress exPAND

                     CONS        Connection Oriented Network Service [ISO]

                         CPE        Customer Premise Equipment

                        CPY        Central Processor Unit

                        CRC        Cyclic Redundancy Check

                     CRTC        Canadian Radio and Television Commission

                           CS        Convergence Sublayer

                        CSC        Common Signaling Channel

                    CSMA        Carrier Sense Multiple Access

             CSMA/CD        Carrier Sense Multiple Access with Collision Detection

                         CT2        Cordless Telephone 2

                         CT3        Cordless Telephone 3

                      CTIA        Cellular Telephone Industry Association


                          DA        Destination Address field

                        DBS        Direct Broadcast Satellite

                      DCM        Digital Carrier Module

                        DCS        Digital Cellular System; Digital Channel Service; Digital Cross-connect System

                        DCT        Digital Cordless Telephone

                       DDD        Direct Distance Dialing

                        DDS        Digital Data Service

                        DEC        Digital Electronic Corporation

                     DECT        Digital European Cordless Telecommunications

                         DID        Direct Inward Dial

                       DMS        Digital Multiplexing System

                       DNA        Digital Network Architecture [Decnet]

                    DNHR        Dynamic Non-Hierarchical Routing

                       DOD        Direct Out Dial

                           DP        Dial Pulse

                        DPO        Dial Pulse Originating

                        DPT        Dial Pulse Terminating

                    DQDB        Distributed Queue Dual Bus [IEEE]

                  DQPSK        Differential Quadrature Phase Shift Keying

                       DS-0        Digital Signal type 0, 0 – 64 Kbps PCM channel

                       DS-1        Digital Signal type 1, 24xDS-0 + 1 signaling bit (1.544 Mbps)

                     DS-1c        DS-1 concatenated [2xDS-1]

                       DS-3        Digital Signal type 3, 28xDS-1 (44.736 Mbps)

            DS-CDMA        Direct Sequence Code Division Multiple Access

                   DSMA        Data Sense Multiple Access [Ardis]

                        DSP        Digital Signal Processing

                        DSU        Data Service Unit

                        DSX        Digital cross-connect

                    DTMF        Dual Tone Multiple Frequency

                          DX        Digital eXchange

                       DXC        Digital cross (X) Connect


                         EBS        Electronic Business Set

                      E&M        Ear and Mouth; a signaling method

                     ECSA        Exchange Carriers Standards Association

                         EIA        Electronics Industries Association

                           EO        Electro-Optical

                       EOM        End Of Message

                  ERMES        European Radio MEssaging System

                         ESF        Extended Super Frame

                          ESI        External Synchronization Interface

                         ESS        Electronic Switching System

                       ESTI        European Telecommunications Standards Institute

                        ETB        End of Transmission Block

                        ETO        Equalized Termination Only

                        ETR        Early Token Release

                        ETX        End Of teXt


                              F        Flag

                        FCC        Federal Communication Commission [US]

                     FCOT        Fiber Central Office Terminal

                         FCS        Frame Check Sequence

                        FDD        Frequency Division Duplex

                      FDDI        Fiber Distributed Data Interface (ANSI)

                       FDM        Frequency Division Multiplexing

                   FDMA        Frequency Division Multiple Access

                        FDS        Fiber Distribution Shelf

                         FEC        Forward Error Correction

                         FEP        Front End Processor

                          FM        Frequency Modulation

                           FR        Frame Relay

                         FSR        Frequency Selective Ringing

                         FST        Fiber Services Terminal

                         FT1        Fractional T-1

                         FTP        File Transfer Protocol

                           FX        Foreign eXchange

                        FXO        Foreign eXchange Office

                        FXS        Foreign eXchange Station [or services]


                       Gbps        Giga bits per second

                        GFC        Generic Flow Control

                      GFSK        Gaussian filtered Frequency Shift Keying

                    GMSK        Gaussian filtered Minimum Shift Keying

                    GOSIP        Government Open System Interconnection Profile

                       GSM        Groupe Speciale Mobile; Global System for Mobile communication


                        HCS        Header Check Sequence [DQDB]

                     HD3B        High-Density 3rd order Binary code

                     HDLC        High-level Data Link Control [ISO]

                     HDTV        High Definition TeleVision

                        HEC        Header Error Control

            HIPERLAN        HIgh Performance European Radio LAN

                       HOB        Head Of Bus [DQDB]

                        HRC        Hybrid Ring Control

                     HSLN        High Speed Local Network


                        IBM        International Business Machines Corp.

                      ICMP        Internet Control Message Protocol

                            ID        IDentification

                      IDDD        International Direct Distance Dialing

                       IDLC        Integrated Digital Loop Carrier

                          IEC        Inter-Exchange Carrier

                                        International Electrotechnical Commission

                        IEEE        Institute of Electrical and Electronic Engineers

                      IMTS        Improved Mobile Telephone Service

                     INMS        Integrated Network Management System

                            IP        Internet Protocol

                        IPv6        Internet Protocol version 6

                         IPX        Internetwork Packet eXchange protocol [Novell]

                          IRL        Input Return Loss

                      ISDN        Integrated Services Digital Network

             ISDN BRA        ISDN Basic Rate Access; otherwise known as 2B+D

             ISDN PRA        ISDN Primary Rate Access

                   ISDN T        ISDN T interface

                  ISDN U        ISDN U interface

                      ISDU        Isochronous Service Data Unit [DQDB]

                         ISO        International Standards Organization

                        ISW        Inverted Synchronization Word

                         ITU        International Telecommunications Union

                         IVD        Integrated Voice Data

                      IVDT        Integrated Voice Data Terminal

                         IXC        Inter-eXchange Carrier


                       JPEG        Joint Photographic Expert group

                         JTC        Joint Techical Committee


                       LAN        Local Area Network

                    LAP-B        Link Access Procedure Balanced [X.25]

                    LAP-D        Link Access Protocol D channel [ISDN]

                        LAS        Local Analog Switch

                    LATA        Local Access and Transport Area

                       LCM        Line Card Module

                     LCAP        Local Craft Access Panel

                        LDS        Local Digital Switch

                         LEC        Local Exchange Carrier

                        LEO        Low Earth Orbit

                        LGC        Line Group Controller

                          LIC        Line Interface Controller

                         LLC        Logical Link Control

                         LSB        Least Significant Bit

                         LSS        Locally Switched Services; services which terminate at the local office

                           LT        Line Termination

                         LTE        Line Terminating Equipment [SONET]


                      MAC        Media Access Control

                      MAN        Metropolitan Area Network

                      MAU        Media Attachment Unit; Multistation Access Unit

                       MBC        Meteor Burst Communications

                       MBS        Meridian Business Services [or set]

                        MCI        Microwave Communications Inc.

                   MDMS        Mobile Data Base Station [CDPD]

                       MDF        Main Distribution Frame

                    MD-IS        Mobile Data Intermediate System [CDPD]

                      M-ES        Mobile End System [CDPD]

                      MIDI        Music Industry Digital Interface

                    MIME        Multipurpose Internet Mail Extensions

                      MIPS        Millions of Instructions Per Second

                       MoU        Memorandum of Understanding

                     MPEG        Motion Picture Expert Group

                    MTSO        Mobile Telecommunications Switching Office

                      MTX        Mobile Telephone eXchange

                      MUX        MUltipleXer


                    NACK        Negative ACKnowledgment

                 NAMPS        Narrow band AMPS

                        NCP        Network Control Program

                           NE        Networking Element

                NetBIOS        Network Basic Input/Output System protocol

                        NFS        Network File Server

                        NLS        Non-Locally Switched services; services which terminate and are switched at a remote office

                         NM        Network Modules

                      NMT        Nordic Mobile Telephone

                         NNI        Network Node Interface

                        NOS        Network Operating System

                        NRZ        Non-Return to Zero

                      NRZI        Non-Return to Zero with Inversion

                        NSS        Non-Switched Services: use dedicated lines

                          NT        Northern Telecom

                    NorTel        Northern Telecom


                      OAM        Operation Administration and Maintenance

                OAM&P        Operation, Administration, Maintenance, & Provisioning

                       OC-1        Optical Carrier 1; an STS-1 signal optically encoded

                       OC-3        Optical Carrier 3; an STS-3 signal optically encoded

                       ONU        Optical Network Unit

                        OPC        OPerations Controller

                        OPX        Off Premises Extension

               OPX intra        an OPX served by a different CO

               OPX inter        an OPX served by the same CO

                  OQPSK        Offset Quadrature Phase Shift Keying

                           OS        Operating System

                         OSI        Open Systems Interconnection


                          PA        Pre-arbitrated Access [DQDB]

                     PABX        Private Automatic Branch eXchange

                     PACK        Positive ACKnowledgment

                       PAD        Packet Assembler Disassembler [X.25]

                        PBX        Private Branch eXchange

                        PCN        Personal Communications Network

                         PCS        Personal Communications System/Service

                      PCSS        Personal Communications Satellite Services

                        PDH        Plesiochronous Digital Hierarchy

                        PDN        Public Data Networks

                        PDU        Protocol Data Unit

                        PHY        PHYsical layer

                           PL        Pad Length

                      PLCP        Physical Layer Convergence Procedure [DQDB]

                          PM        Peripheral Module; Performance Monitoring; Physical Medium

                       PMD        Physical layer Medium Dependent

                        POH        Path OverHead [SONET]

                        PON        Passive Optical Network

                        POP        Point of Presence

                        POS        Point Of Sale

                      POTS        Plain Ordinary Telephone Service

                         PPP        Point to Point Protocol

                      PPSN        Public Packet Switched Network

                        PRA        PRimary Access rate i.e. 23B+D or 30B+D

                          PRI        Primary Rate Interface [ISDN]

                      PSDS        Public Switched Digital Service

                      PSTN        Public Switched Telephone Network

                     PTAT        Private Trans Atlantic Telecommunications

                        PTT        Post, Telegraph and Telephone

                        PVC        Permanent Virtual Circuit


                          QA        Queued Arbitrated access; Quality Assurance

                    QCPM        Quadrature Continuous Phaseshift Modulation

                        QoS        Quality of Service

                     QPSK        Quadrature Phase Shift Keying

                     QPSX        Queued Packet and Synchronous eXchange


                     RACE        Research and development in Advanced Communications for Europe

                     RBOC        Regional Bell Operating Company

                      RDPS        Reverse Direction Protection System

                        RFT        Remote Fiber Terminal

                       RISC        Reduced Instruction Set Computer

                          RQ        ReQuest

                           RZ        Return to Zero


                       SAA        Service Adaptive Access

                        SAP        Service Access Point

                        SAR        Segmentation And Reassembly

                         SCP        Service Control Points

                        SDH        Synchronous Digital Hierarchy

                      SDLC        Synchronous Data Link Control [IBM]

                        SDU        Service Data Unit

                   S/DMS        SONET Digital Multiplexing System

                           SF        Super Frame

                          SIP        Smds Interface Protocol

                       SLIC        Subscriber Line Interface Circuit

                    SMDS        Switched Multi-megabit Data Service

                     SMTP        Simple Mail Transfer Protocol

                       SNA        Systems Network Architecture [IBM]

                         SNI        Subscriber Network Interface [SMDS]

                    SNMP        Systems Network Management Protocol

                        SOH        Section OverHead

                   SONET        Synchronous Optical NETwork

                   SPADE        Single channel, Pulse code modulation, multiple Access, Demand assignment Equipment

                         SPE        Synchronous Payload Envelope [SONET]

                  SPRING        Shared Protection RING

                         SSB        Single Side Band

                     SSDN        Special Services Digital Network

                       STM        Synchronous Transfer Mode

                    STM-1        Synchronous Transport Mode level 1 [3xSTS-1, STS-3c]

                         STP        Shielded Twisted Pair; Spanning Tree Protocol

                         STS        Synchronous Transport Signal

                     STS-1        Synchronous Transport Signal level 1 [51.84 Mbps]

                     STS-3        Synchronous Transport Signal level 3 [155.52 Mbps]

                   STS-3c        Concatenated STS-3

                        SVC        Switched Virtual Circuit; Signaling Virtual Channel

                         SW        Synchronization Word

                        SYN        SYNchronous idle


                          TA        Terminal Adapter

                     TACS        Total Access Communications System

                      TADI        Time Assignment Data Interpolation

                      TASI        Time Assignment Speech Interpolation

                       TBM        Transport Bandwidth Manager

                       TCM        Time Compression Multiplexing

                   TCP/IP        Transmission Control Protocol/Internet Protocol

                       TDD        Time Division Duplex

                      TDM        Time Division Multiplexing

                   TDMA        Time Division Multiple Access

                           TE        Terminal Equipment

                      Telco        Telephone company

                        THL        Trans-Hybrid Loss

                         TIA        Telecommunications Industry Association

                           TP        Twisted Pair; Tip Party

                           TR        Technical Report

                          TSI        Time Slot Interchange

                         TSS        Transport Services Shelf; a component of DMS AccessNode


                     UDLC        Universal Digital Loop Carrier

                        UDP        User Data Protocol [internet]

                    UMTS        Universal Mobile Telecommunications Service

                         UNI        User Network Interface

                        UTP        UnTwisted Pair


                       VAN        Value Added Network

                        VBR        Variable Bit Rate

                           VC        Virtual Channel [ATM]; Virtual Call [X.25]

                         VCI        Virtual Channel Identifier

                           VF        Voice Frequency

                       VLSI        Very Large Scale Integration

                           VP        Virtual Path

                          VPI        Virtual Path Identifier

                     VSAT        Very Small Aperture Terminal

                           VT        Virtual Tributary (SONET)

                      VT1.5        VT ~1.5 Mbps [capable of carrying a DS-1]


                     WAN        Wide Area Network

                   WARC        World Administrative Radio Conference

                   WATS        Wide Area Telecommunication Service

                      WBC        Wide Band Channels

                     WDM        Wave Division Multiplexing

                   WWW        World Wide Web


                            XI        X.25 SNA Interconnect


                    ZBTSI        Zero Byte Time Slot Interchange

For Even More Acronyms