A

aoc ADSL overhead control channelAA Administrative AuthorityAAL ATM Adaptive LayerAAR Automatic Alternate RoutingABR Available Bandwidth RateABR Available Bit RateACD Automatic Call DistributionACF Access Coordination FunctionACK AcknowledgmentACM Adress Complete MessageACO Automatic Cut OffACSE Association Control Service ElementACU Alarm Control UnitADC Analog to Digital ConverterADM Add/Drop MultiplexerADM 3X DS3 Add-Drop MultiplexADPCM Adaptive Differential Pulse Code ModulationADSI Analog Display Services InterfaceADSL Asymmetric Digital Subscriber LineADSS All Dielectric Self-SupportingADTS Automated Digital Terminal SystemsAERM Alignment Error Rate MonitorAFI Authority and Format IdentifierAFSK Audio Frequency Shift KeyingAFPS Automatic Facility Protection SwitchingAi Action indicatorAIN Advanced Intelligent NetworkAIS Alarm Indication SignalAIS-L Alarm Indication Signal - LineAIS-P Alarm Indication Signal - PathAIS-V Alarm Indication Signal - Virtual (Tributary)AIU Analog Interface UnitALIT Automatic Line Insulation TestALPS Automatic Loop Protection SwitchingAMA Automatic Message AccountingAMI Alternate Mark InversionAMPS Advanced Mobile Phone ServiceANC Access network ControllerANI Automatic Number IdentificationANSI American National Standards InstituteAON All Optical NetworkAP Access PointAP Action PointAPDU Application Protocol Data UnitAPR Alarm Processing RemoteAPS Automatic Protection SwitchingARD Automatic Ring DownARP Address Resolution ProtocolAS56 Accunet Switched 56ASB Application Specific BitsASCII American Standard Code for Information InterchangeASN.1 Abstract Syntax Notation One

ASP Application Service ProviderASP Assignment Source PointAT Access TandemsATM Asynchronous Transfer ModeATM-LI ATM Link IdentifierATM-PCI ATM Protocol Control InformationATM-SDU ATM Service Data UnitATMM ATM Layer ManagementATU-C ADSL Transceiver Unit - Central office endATU-R ADSL Transceiver Unit - Remote terminal end

B

B3ZS Bipolar 3 Zero SubstitutionB6ZS Bipolar 6 Zero SubstitutionB8ZS Bipolar 8 Zero SubstitutionB8ZS Bipolar 8 Zero SuppressionB-CPE Broadband Customer Premises EquipmentB-ICI Broadband Inter-Carrier InterfaceBAF Bellcore AMA FormatBc Committed Burst SizeBCD Binary Coded DecimalBCM Bit Compression MultiplexerBDFB Battery Distribution Fuse BoardBDCBB Battery Distribution Circuit Breaker BoardBE Block ErrorBECN Backward Explicit Congestion NotificationBER Basic Encoding RulesBER Bit Error RatioBERT Bit Error Rate TesterBFCV Binary Facility Coding ValueBGP Border Gateway ProtocolBIB Backward Indicator BitBIBR Backward Indicator Bit ReceivedBIBT Backward Indicator Bit to be TransmittedBIBX Backward Indicator Bit eXpectedBIP Bit Interleaved ParityBISDN Broadband Integrated Services Digital NetworkBISUP Broadband ISUP (ISDN User Part)BLER Block Error RateBOC Bell Operating CompanyBOM Beginning of MessageBORSCHT Battery feed, Overvoltage protection, Ringing,

Signaling, Coding, Hybrid, and TestingBPOP Building Point of Presencebps Bits Per SecondBPV Bipolar ViolationBRA Basic Rate AccessBRI Basic Rate Interface (ISDN)BRITE Basic Rate Interface Transmission ExtensionBSC Base Station Controller

BSC Bisynchronous Communications (protocol)BSN Backward Sequence NumberBSNR Backward Sequence Number ReceivedBSNT Backward Sequence Number to be TransmittedBSP Bell System PracticeBSRF Basic System Reference FrequencyBSS Base Station SubsystemBSS Basic Service SetBSS Broadband Switching SystemBTS Base Station Transceiver

C

C/R Command/ResponseC/R Control/Response Indication BitCAC Connection Admission ControlCAL Customer Access LineCAP Carrierless Amplitude Phase (modulated)CAP Competitive Access ProviderCAS Channel Associated SignalingCATV Cable televisionCBCU Centralized Broadband Control UnitCBDS Connectionless Broadband Data ServicesCBR Constant Bit RateCBQ Class-Based QueuingCc Committed Burst SizeCCC Clear Channel CapabilityCCE Consistency Check EndCCS Hundred Call SecondsCCIS Common Channel Inter-office SignalingCCITT Comite Consultatif Internationale Telegraphique

et TelephoniqueCCITT International Telegraph and Telephone Consultative CommitteeCCR Consistency Check requestCCR Customer Controlled ReconfigurationCCS Common Channel SignalingCCS Hundred Call SecondsCCSA Common Control Switching ArrangementCCU Common Control UnitCDMA Code Division Multiple AccessCDO Community Dial OfficeCDPD Cellular Digital Packet DataCEI Connection Endpoint IdentifierCEPT Committee of European Postal & Telephone (authorities)CES Circuit Emulation ServiceCES Connection Endpoint SuffixCEV Controlled Environment VaultCF Coin FirstCFA Carrier Failure AlarmCGA Carrier Group Alarm

CGW Customer GatewayCH Cell HeaderCHTML Compact Hyper Text Markup LanguageCI Customer InstallationCID Craft Interface DeviceCIR Committed Information RateCIU Communications Interface UnitCLEC Competitive Local Exchange CarrierCLLM Consolidated Link Layer ManagementCLNP Connectionless-mode Network ProtocolCLNS Connectionless Network ServicesCLP Cell Loss Priority (CLP Bit)CLS Connectionless ServiceCMIP Common Management Information ProtocolCMIS Common Management Information ServiceCMISE Common Management Information Service ElementCNM Customer Network ManagementCO Central OfficeCOC Central Office ConnectionCODEC COder-DECoderCOFA Change of Frame AlignmentCOM Continuation of MessageCOMPANDER COMpressor/exPANDERCOPS Common Open Policy ServiceCORBA Common Object Request Broker ArchitectureCOT Central Office TerminalCP Cell PayloadCP Customer PremisesCPCS Common Part Convergence SublayerCPE Customer Premises EquipmentCPI Computer-PBX InterfaceCPNI Customer Proprietary Network InformationCPP Calling Party PaysCPS Customer Premises SystemCPU Central Processor UnitCR Call ReferenceCRC Cyclic Redundancy CheckwordCRM Circuit Reservation MessageCRS Cell relay ServiceCRV Call Reference ValueCS Convergence SublayerCSA Canadian Standards AssociationCSA Carrier Service AreaCSAP Core Service Access PointCSC Common Signaling ChannelCSDU Core Service Data UnitCSH Convergence Sublayer HeaderCSMA/CD Carrier Sense Multiple Access/Collision DetectCU Channel UnitCS Convergence SublayerCSA Carrier Serving AreasCSR Consistency Check RequestCST Convergence Sublayer TrailerCSU Channel Service UnitCS-PDU Convergence Sub-layer PDUCT Channel TerminationCT Computer Telephony

CTU Channel Test UnitCU Channel UnitCUG Closed Users GroupCV Coding ViolationCVSD Continuously Variable Slope Delta ModulationCPE Customer Premise EquipmentCPI Computer-PBX InterfaceCTS Clear to SendCV Coding ViolationCUG Closed Users GroupCVSD Continuously Variable Slope, Delta ModulationCWC Center Weight Control

D

DA Distribution AreaDACS Digital Access and Cross ConnectDAVIC Digital Audio Video CouncilDBS Direct Broadcast SatellitedB deciBelldBm dB relative to one milliwattDBN Dial-Back NumberdBrn dB relative to noisedBrnc dB relative to noise (C-Notch or C-Message)DCB Digital Channel BankDCC Data Communications ChannelDCC Data Country CodeDCCX Direct Circuit Control ExchangeDCE Data Circuit-terminating EquipmentDCE Data Communications EquipmentDCF Distributed Coordination FunctionDCN Data Communications Network DCS Digital Cross-connectDCSs Digital Cross-Connect SystemDDD Direct Distance DialingDDS Dataphone Digital Service (registered trademark of AT&T C0.)DDS Digital Data ServiceDDSD Delay Dial Start DialDE Discard EligibilityDF Distributing FrameDFL Distributed Feedback LaserDFRI Datacom Reference Frame InputDHCP Dynamic Host Configuration ProtocolDID Directed Inward DialingDL Data LinkDLC Digital Loop CarrierDLCI Data Link Connection IdentifierDLL Dial Long LineDLU Digtal Line UnitDM Disconnected Mode

DMI Digital Multiplex InterfaceDMPB Digital Multipoint BridgingDMS Digital Multiplex SystemDMT Discrete MultitoneDNIC Data Network Identification CodeDNIC Data Network Interface (2B+D ISDN)DNIS Dialed Number Identification ServiceDNS Domain Name SystemDOCSIS Data Over Cable Service Interface SpecificationDoV Data Over VoiceDP Dial PulseDPA Distributed Power ArchitectureDPBX Digital Private Brance ExchangeDPC Destination Point CodeDPCM Differential Pulse Code ModulationDPDU Data (link) Protocol Data UnitDPL Digital Power LineDPO Dial Pulse OriginateDPT Dial Pulse TerminateDPT Dynamic Packet TransportDS0 Digital Signal Zero - 64 Kb/s data/voice chanDS1 Digital Signal One (DS0 x 24 mux = 24 DS0)DS2 Digital Signal 2 (DS1 x 4 mux = 96 DS0)DS3 Digital Signal 3(DS2 x 7 mux = 672 DS0)DSI Digital Speech InterpolationDSL Digital Subscriber LineDSLAM Digital Subscriber Line Access MultiplexerDSODP Digital Service Office DataportDSP Digital Signal ProcessorDSSS Direct Sequence Spread SpectrumDSU Digital Service UnitDSX Digital Signal Cross-connectDSSS Direct Sequence Spread SpectrumDTAU Digital Test Access Unit DTE Data Terminal EquipmentDTF Dial Tone FirstDTF Digital Transmission FacilityDTI Digital Trunk InterfaceDTMF Dual Tone Multiple FrequencyDTR Data Terminal ReadyDTS Digital Terminal SystemsDTS Digital Transmission SystemsDTU Data Terminal UnitDUP Data User PartDVI Digital Video InterleavedDWDM Dense Wavelength Division MultiplexingDX DuplexDXC Digital Cross ConnectDXI Data Exchange InterfaceD/I Drop and InsertD3 Third generation channel bank

(24 chans on T1)D4 Fourth generation channel bank

(48 voice chans on 2 T1's or 1 T-1C)

E

EA Extended AddressEAI Enterprise Application IntegrationEBCDIC Extended Binary Coded Decimal Information CodeEC Echo CancelingEC-n Electrical Carrier (e.g., EC-1)ECSA Exchange Carriers Standards AssociationEDFA Erbium-Doped Fiber AmplifierEDI Electronic Data InterchangeEDSX Electronic Digital Signal Cross-ConnectEFCI Explicit Forward Congestion IndicationEFD Event Forwarding DiscriminatorEFS Error Free SecondEGP Exterior Gateway ProtocolEIM Errored Interval MonitoredELEC Ethernet Local Exchange CarrierELFEXT Equal Level Far End CrosstalkEM Element ManagerEML Element Management LayerEMI Electromagnetic InterferenceEMS Element Management SystemEOC Embedded Operations ChannelEOM End of MessageEPSCS Enhanced Private Switch Controlled SystemERL Echo Return LossERM Explicit Rate MarketingES Errored SecondESF Extended Super FrameESG Enhanced Service GatewayESFDL Extended Super Frame Data-LinkESI End System IdentifierESS Electronic Switching SystemET Exchange TerminationETN Electronic Tandem NetworkETSI European Telecommunications Standards InstituteEXZ Excess Zeros

F

FAS Frame Alignment SignalFAW Frame Alignment WordFB Framing BitFBWA Fixed Broadband Wireless AccessFCC Federal Communications CommissionFCS Frame Check SequenceFDDI Fiber Distributed Data Interface

FDI Feeder Distribution InterfaceFDL Facilities Data LinkFDLC Fujitsu Digital Loop CarrierFDM Frequency Division MultiplexingFE Frame synchronization bit error EventFEAC Far End Alarm and ControlFEBE Far End Block ErrorFEBE-f Far End Block Error Count - fast dataFEBE-i Far End Block Error Count - interleaved dataFEC Forward Error CorrectionFECC-f Forward Error Correction Count - fast dataFECC-i Forward Error Correction Count - interleaved dataFECN Forward Explicit Congestion NotificationFELB Far End Loop BackFERF Far End Receive FailureFEXT Far-End Cross TalkFHSS Frequency Hopping Spread SpectrumFI Facility IdentificationFIB Forward Indicator BitFIBR Forward Indicator Bit ReceivedFIBT Forward Indicator Bit to be TransmittedFIBX Forward Indicator Bit eXpectedFIC Frame Identification CodeFIFO First In First OutFISU Fill-In Signal UnitFITL Fiber In The LoopFLL Fixed Loss LoopFOTS Fiber Optical Transmission SystemFPS Framing Pattern SequenceFR-SSCS Frame Relay Service Specific Convergence Sub-layerFRAD Frame Relay Access DeviceFRAD Frame Relay Assembler/DisassemblerFRF-LMI Frame Relay Forum - Local Management InterfaceFRMR Frame RejectFR PVC Frame Relay Permanent Virtual ConnectionFRS Frame Relay ServiceFRSS Frame Relay Switching System FSK Frequency Shift KeyingFSN Forward Sequence NumberFTAM File Transfer, Access and ManagementFTP File Transfer ProtocolFTSC Federal Telecommunications Standards CommitteeFTTC Fiber to the CurbFTTH Fiber to the HouseFTTL Fiber to the LoopFTTN Fiber to the NeighborhoodFT1 Fractional T1FUNI Frame (relay) User Network InterfaceFXO Foreign Exchange OfficeFX Foreign ExchangeFXO Foreign Exchange OfficeFXS Foreign Exchange Subscriber

G

GFC Generic Flow ControlGFI General Format IdentifierGGP Gateway to Gateway ProtocolGGSN Gateway GPRS Support NodeGOS Grade of ServiceGOSIP Government Open System Interconnection ProfilesGPRS General Packet Radio ServiceGPRS General Packet Radio SystemGPS Global Positioning SystemGS Ground StartGSM Global System for Mobile (telecommunications)GTXC Global Telephone Exchange Carrier

H

HCDS High Capacity Digital ServicesHCV High Capacity VoiceHDB3 High-Density Bipolar Three-Bit substitutionHDLC High (level) Data Link ControlHDML Handheld Device Markup LanguageHDSL High (Data Rate) Subscriber LineHDSL2 High (Data Rate) Subscriber Line

(w/6dB noise margin)HDT Host Digital TerminalHEC Header Error ControlHFC Hybrid Fiber CoaxHLR Home Location RegisterHPC High Probability of CompletionHSCWD High Speed Circuit Switched DataHTML Hypertext Markup LanguageHTTP Hypertext Transfer ProtocolHTU HDSL Transmission UnitHTU-C HDSL Transmission Unit - Central OfficeHTU-R HDSL Transmission Unit - Remote

I

IAA Initial Address AcknowledgementIAB Internet Advisory Board

IAC Initial Alignment ControlIAD Integrated Access DeviceIAM Initial Address MessageIAR Initial Address RejectIAT Integrated Access TerminalIC-POT Interexchange Carrier-Point of TerminationICCF Interexchange Carrier Compatibility ForumICD International Code DesignatorICI Inter-Carrier InterfaceICIP Inter-Carrier Interface ProtocolICL Inserted Connection LossICMP Internet Control Message ProtocolICOT Inner City and Outstate TrunkIDCP Internet Device Control ProtocolIDF Intermediate Distribution FrameIDLC Integrated Digital Loop CarrierIDS Intrusion Detection SystemIDT Information Distribution CompanyIDT Integrated Digital TerminalIDU Interface Data UnitIEEE Institute of Electrical and Electronics EngineersIG Interface GroupIGP Interior Gateway ProtocolIIME Intra-network, Inter-SSS Mapping EntityIIS Internet Information ServerISID Idle Signal IdentificationISSP Interim Interswitch Signaling ProtocolILEC Incumbent Local Exchange CarrierILEC Independent Local Exchange CarrierILMI Interim Local Management InterfaceIMP Interface Message ProcessorsIMS Interactive Multimedia ServerIMSI International Mobile Subscriber IdentityIN Intelligent NetworkINA Information Network ArchitectureINE Intelligent Network ElementIO Inter-OfficeIOC Inter-Office ChannelIP Intelligent PeripheralIP Internet ProtocolIPSec Internet Protocol SecurityIPM Interpersonal Messaging SystemIPS Instructions Per SecondISDN Integrated Services Digital NetworkISDNUP Integrated Services Digital Network User PartISM Instrumentation, Scientific, and MedicalISO International Standards OrganizationISP Internet Service ProviderISSI Inter-Switching System InterfaceISSIP Inter-Switching System Interface ProtocolISUP ISDN User PartITFS Instructional Television Fixed ServicesITU International Telecommunication UnionIWF Inter-Working FunctionIWU Inter-Working UnitIXC Interexchange Carrier

J

JIS Jurisdictional Interstate Service

K

L

LAN Local Area NetworkLAN PHY LAN Physical LayerLANE Local Area Network EmulationLAP-D Link Access Protocol-D channelLAPB Link Access Protocol BalancedLAPD Link Access Procedure D channelLATA Local Access and Transport AreaLAW Local Area WirelessLC Load CoilLC Loop ClosureLCA Line Circut AddressLCF Loop Current FeedLCFO Loop Current Feed OpenLCGN Logical Channel Group NumberLCN Logical Channel NumberLCP Link Control ProtocolLDAP Lightweight Directory Access ProtocolLDC LATA Distribution ChannelLDF Local Distribution FrameLDM Limited Distance ModemLDN Listed Directory NumberLDS Local Digital SwitchLEC Local Exchange CarrierLEN Line Equipment NumberLES LAN Emulation ServicesLET Line Equipment TransferLGE Loop- or Ground-Start ExchangeLGS Loop- or Ground-Start SubscriberLIDB Line Information DatabaseLLB Line Loop BackLLC Logical Link Control

LLSC signaling Link management; Link Set ControlLMC Loop Maintenance CenterLMDS Local Multipoint Distribution ServiceLMI Local Management InterfaceLMOS Loop Maintenance Operations SystemLMU Line Monitor UnitLNP Local Number PortabilityLO Loop OpenLOF Loss Of FrameLOH Line OverheadLOP Loss Of PointerLOP-L Loss Of Pointer - LineLOP-P Loss Of Pointer - PathLOP-V Loss Of Pointer - VirtualLOS Line of SightLOS Loss Of SignalLOSW Loss Of Synchronous Word LPC Linear Predictive CodingLPDP Local Policy Decision PointLPU Line Protection UnitLRB Loop Reverse BatteryLRN Local Routing NumberLS Loop StartLSAC signaling Link management; Signaling Link Activity ControlLSAP Link Service Access PointLSC Link State ControlLSLA signaling Link management; Signaling Link ActivationLSLD signaling Link management; Signaling Link DeactivationLSLR signaling Link management; Signaling Link RestorationLSMS Local Service Management SystemLSOA Local Service Order AdministrationLSSGR LATA Switching Systems Generic RequirementsLSSU Link Status Signal UnitLSU Line Switch UnitLT Line TerminationLTE Line Terminal EquipmentLU Line UnitLULT Line Unit/Line TerminationLUNT Line Unit Network TerminationLXT Local Exchange Terminal

M

MAC Media Access ControlMAN Metropolitan Area NetworkMAPDU Management Application Protocol Data UnitMAT Metropolitan Area TrunkMB Maintenance BusyMCU Multiplexer Control UnitMDCP Media Device Control Protocol

MDF Main Distribution FrameMDS Multipoint Distribution ServiceMDTP Media Device Transport Protocol MF Multiple FrequencyMFAS Multi-Frame Alignment SignalMGCP Media Gateway Control ProtocolMRF Multilink Frame RelayMGCP Media Gateway Control ProtocolMIB Management Information BaseMIME Multipurpose Internet Mail ExtensionMIX Multimedia Internet ExchangeMJU Multi-Junction UnitMLHG Multi-Line Hunt GroupMLM Multi-Longitudinal ModeMLT Mechanized Loop TestingMLT Metalic Loop TestMMDX Multimedia Data ServicesMMDS Multichannel Multipoint Distribution ServiceMMDS Multimedia Data ServicesMO Managed ObjectMOC Managed Object ClassesMOOS Manual Out-OF-ServiceMPLS Multi-Protocol Label SwitchingMPLS Multi-Protocol Layer SwitchingMPoA Multiple Protocol over ATMMSA Metropolitan Statistical AreaMSDM Multipoint Substrate Data MuxMSO Multiple Service OperatorMTAU Metalic Test Access UnitMTP Message Transfer PartMRVT MTP Routing Verification TestMTS Message Telephone SystemMTSO Mobile Telephone Switching OfficeMUB MultiUse Bearer serviceMULDEM MULtiplexer/DEMultiplexerMUX MULtiplexer/DEMultiplexerMVNO Mobile Virtual Network Operator

N

N(r) Receive Sequence NumberN(s) Send Sequence NumberNACK Negative ACKnowledgementNADH North American Digital HierarchyNAK Negative AcknowledgementNANP North American Numbering PlanNAS Network Attached StorageNAT Network Attached StorageNAT Network Address TranslationNC Network Channel

NCC Network Communications ControllerNCI Network Channel InterfaceNCP Network Control PointNCP Network Control ProtocolNCTE Network Channel Terminating EquipmentNDF New Data FlagNE Network ElementNEXT Near End Cross TalkNFAS Non-associated Facility SignalingNGDLC Next Generation Digital Loop CarrierNGN Next Generation NetworkNGW Network GatewayNI Network InterfaceNI Network InterfaceNI-1 National ISDN-1NI-2 National ISDN-2NIC Network Interface CardNIU Network Interface UnitNLPID Network Level Protocol IDNLOS Near Line of SightNMA Network Management and AdministrationNMA Network Monitoring and AnalysisNMC Network Management CenterNML Network Management LayerNMP Network Management ProtocolNMS Network Management SystemNNI Network Node InterfaceNNI Network-to-Network InterfaceNNTP Network News Transport ProtocolNOC Network Operations CenterNOS Network Operating SystemNOTE Network Office Terminating EquipmentNPA Numbering Plan AreaNPAC Number Portability Administration CenterNPDU Network Protocol Data UnitNPRN Network Performance Report MessageNPI Numbering Plan IdentificationNRIC National Reliability and Interoperatability CouncilNRZ Non-Return to ZeroNSA Non-Service AffectingNSC Network Service CenterNSF Network Specific FacilitiesNSI Network Service InterfaceNSP National Signaling PointNTE Network Terminating EquipmentNTT Numbered Test TrunkNYIIX New York International Internet Exchange

O

OADM Optical Add-Drop MultiplexerOAM Operations, Administration, and MaintenanceOAM&P Operations, Administration, Maintenance

& ProvisioningOAMP Operations, Administration, Maintenance

ProvisioningOC-n Optical Carrier (e.g., OC-3)OC-x Optical Carrier (e.g., OC-3)OCPD Over Current Protection DeviceOCU Office Channel UnitOCUDP Office Channel Unit Data PortOE Originating EquipmentOEO Optical-Electrical-OpticalOFA Optical Fiber AmplifierOFDM Orthogonal Frequency Division MultiplexingOIM Operations Interface ModuleOLNS Originating Line Number ScreeningOLP On-Line ProvisioningOM Operational MeasurementONU Optical Network UnitOOD Object Oriented DesignOOF Out Of FrameOOS Out Of ServiceOOS Out Of SynchronizationOPN Outage Performance MonitoringOPS/INE Operations System/Intelligent Network ElementOPX Off Premise ExtensionOR Office RegeneratorORB Office Repeater BayOS Operations SystemOSI Open System InterconnectionOSI Open System InterfaceOSPF Open Shortest Path FirstOSS Operation Support SystemOSS Operator Services SystemOTC Operating CompanyOTDR Optical Time Domain ReflectometerOUI Organizationally Unique Identifier

P

P/F Poll/Final BitPA Pointer AdjustmentPABX Private Automatic Branch ExchangePAD Packet Assembler / DisassemblerPAM Pass Along MessagePAM Pulse Amplitude ModulationPAW Personal Area WirelessPBD Power Board

PBX Private Branch ExchangePCF Point Coordination FunctionPCI Protocol Control InformationPCM Pulse Code ModulationPCMCIA Personal Computer Memory Card International AssociationPCS Personal Communications ServicesPCTF Per-Call Test FailurePCU Packet Control UnitPD Protocol DiscriminatorPDH Plesiochronous Digital HierarchyPDI-P Payload Defect Indicator - PathPDI V Payload Defect Indicator - VirtualPDN Public Data NetworkPDP Policy Decision PointPDU Protocol Data UnitPEP Policy Enforcement PointPFDL Policy Framework Definition LanguagePFM Packet Forwarding modulePGTC Pair Gain Test Controller PGS Pair Gain SystemPHS Packet Handling SystemPHY Physical Layer (abbrev.)PHY-PCI Physical Layer Protocol Control InformationPHY-SAP Physical Layer-Service Access PointPHY-SDU Physical Layer-Service Data UnitPHYM Physical Layer ManagementPIB Policy Information BasePID Path IdentificationPIP Pre-Impulsing PulsePJC Pointer Justification CountPKI Public Key InfrastructurePL Private LinePLA Programmable Logic ArrayPLAR Private Line Automatic RingdownPLB Payload Loop BackPLC Power Line CarrierPLCP Physical Layer Convergence ProtocolPLS Private Line servicePM Performance MonitoringPMD Physical Media DependentPNNI Private Network Node InterfacePOC Positive Outage ControlPOH Path OverheadPON Passive Optical NetworkPOP Point Of PresencePOP Post Office ProtocolPoS Packet Over SONETPOS Point of SalePOT Point Of TerminationPOTS Plain Old Telephone ServicePOTS Plain Old Telephone SystemPPP Point to Point ProtocolPPSN Public Packet Switched NetworkPRA Primary Rate AccessPRD Pseudo-Random DownstreamPRI Primary Rate Interface (ISDN)PRBS Pseudo-Random Binary Sequence

PRBS Pseudo-Random Bit SequencePRM Performance Report MessagePRS Primary Reference SourcePRU Pseudo-Random UpstreamPSELFEXT Power Sum Equal Far End Cross TalkPSDM Premium Substrate Data MuxPSDS Public Switched Digital ServicePSK Pulse Shift KeyingPSNEXT Power Sum Near End Cross TalkPSTN Public Switched Telephone NetworkPSX Power System ExchangePT Payload TypePTE Path Terminal EquipmentPTI Payload Type IndicatorPTT Postal, Telephone and Telegraph AuthorityPVC Permanent Virtual Circuit

Q

QAM Quadrature Amplitude ModulationQoS Quality of ServiceQPA Quality Performance AnalysisQRS Quasi Random SignalQRSS Quasi Random Signal Sequence

R

R RingRAD Remote Antenna DriverRAI Remote Alarm IndicationRALB Resource All BusyRARP Reverse Address Resolution PtotocolRAS Remote Access ServerRAS Remote Access ServiceRASP Remote Antenna Signal ProcessingRBOC Regional Bell Operating CompanyRBS Robbed Bit SignalingRC Retransmission CounterRCV ReceiveRD Routing DomainRDF Remote Distribution FrameRDI Remote Defect IndicatorRDI-L Remote Defect Indicator - LoopRDI-P Remote Defect Indicator - Path

RDI-V Remote Defect Indicator - VirtualRDT Remote Digital TerminalRE Relaying EntityREN Ringer Equivalent NumberRFCs Request For CommentsRFI Radio Frequency InterferenceRIP Routing Information ProtocolRLCI Receive Line Clock InputRLDI Receive Line Data InputRM Resource ManagementRNC Radio Network ControllerRNR Receive Not ReadyROH Receiver Off HookROS Remote Operations ServiceROSE Remote Operations Service ElementRPR Resilient Packet RingRR Receive ReadyRSS Remote Switching SitesRSS Remote Switching SystemRSU Remote Switching UnitRT Remote TerminalRTA Rural Trading AreaRTB Retransmission BufferRTPC signaling Route management; transfer Prohibited ControlRTR Retransmission indicatorRTS Request To SendRTU Remote test UnitRX ReceiveRZ Return to Zero

S

SAA Service Adaptive AccessSABME Set Asynchronous Balance Mode ExtenderSAN Storage Area NetworkSAM Service Access MultiplexerSAMI SAM InterfaceSAN Storage Area NetworkSAP Service Access PointSAPI Service Access Point IndetifierSAR Segmentation And ReassemblySAR-PDU Segmentation and Reassembly PDUSBX Small Business ExchangeSC-FDE Single Carrier Frequency Domain EqualizationSCC Switching Control CenterSCCP Signaling Connection Control PartSCCS Switching Control Center SystemSCE Service Creation EnvironmentSCP Service Control PointSDCU Synchronous Data Channel Unit

SDH Synchronous Digital Hierarchy (SONET)SDLC Synchronous Data Link ControlSDP Session Description ProtocolSDM Substrate Data MuxSDN Software Defined NetworkSDP Service Definition and ProvisioningSDP Session Description ProtocolSDSL Symmetric Digital Subscriber LineSEAL Simple and Efficient Adaptation LayerSEL Selector FieldSEFL Single Ended Fault LocatingSEP Signaling End PointSES Severe Errored SecondsSF Single FrequencySF Status FieldSF SuperframeSGCP Simple Gateway Control ProtocolSGML Standard Generic Markup LanguageSGSN Serving GPRS Support NodeSH SAR Sublayer HeaderSHR Self-Healing RingSINAD Signal-to-Noise Plus Distortion (ratio)SI Service Information octetSIB Status Indication B (busy)SIE Status Indication E (emergency alignment)SIF Signaling Information FieldSIN Status Indication N (normal alignment) SIO Status Indication O (out of alignment)SIP Session Initiation ProtocolSIT Special Information ToneSL Service LayerSLA Service Level AgreementSLIC Subscriber Line Interface CardSLIP Serial Line Interface ProtocolSLIP Serial LIne Internet ProtocolSLS Single Link SetSMASE Systems Management Application Service ElementSMC Switch Maintenance CenterSMDF Subscriber Maintenance Distributing FrameSMDS Switched Multi-megabit Data ServiceSML Service Management LayerSMS Service Management SystemSMS Short Message ServiceSMTP Simple Mail Transfer ProtocolSNA Systems Network ArchitectureSNAP Sub-Network Access ProtocolSNI Subscriber-Network InterfaceSNMP Simple Network Management ProtocolSNR Signal to Noise RatioSO Serving OfficeSO/S Smart Omni-Orderwire StationSOA Service Order AdministrationSOH Section OverheadSOHO Small Office/Home OfficeSONET Synchronous Optical NetworkSP SAR Sublayer PayloadSP Signaling Point

SPC Stored Program ControlSPCS Stored Program Control SystemSPE Synchronous Payload EnvelopeSPID Service Profile IdentifierSPRM Supplementary Performance Report MessageSPQR Senatus et Populus Qui RomaSQR Signal to Quantizing noise RatioSRDM Sub Rate Data MultiplexerSRL Singing Return LossSRM Signaling Route ManagementSRP Spatial Reuse ProtocolSRTS Synchronous Residual Time StampSS Supervisory CenterSS7 Signaling System No.7SSCS Service Specific Convergence SublayerSSL Secure Socket LayerSSP Service Switching PointSSP SCCP Subsystem ProhibitedSSS SMDS Switching SystemST SAR Sublayer TrailerSTDM Statistical Time Division MultiplexerSTE Section Terminal EquipmentSTP Signaling Trasfer PointSTM Synchronous Transfer ModuleSTP Shielded Twisted PairSTP Signaling Transfer PointSTS Synchronous Transfer SignalSTS-1 Synchronous Transport Signal (level)-1SU Signal UnitSUERM Signaling Unit Error Rate MonitorSVC Switched Virtual CallSVC Switched Virtual CircuitSVC Switched Virtual ConnectionSWAP Shared Wireless Access ProtocolSWF Switched FractionalSWF-DS1 Switched Fractional DS1SYN Synchronization CharacterSYNTRAN SYNchronous TRANsmission

T

T TipTA Terminal AdapterTAC Terminal Access CircuitTACS Total Access Communications SystemTALI Transport Adapter Layer InterfaceTAP Test Access PathTAPI Telephony Application Programming InterfaceTASI Time Assigned Speech InterpolationTAU Test Access Unit

TAU Time Assignment UnitTC Terminating ChannelTC Transmission ConvergenceTCA Threshold Crossing AlertTCAP Transaction Capabilities Application PartTCM Tandem Connection MaintenanceTCP Transmission Control ProtocolTCP Transport Control ProtocolTCP/IP Transmission Control Protocol/Internet ProtocolTDM Time Division MultiplexingTDMA Time Division Multiple AccessTDR Time Domain ReflectometerTE Terminal EquipmentTEI Terminal Endpoint IdentifierTELRIC Total Element Long-Run Incremental CostTFO Tandem Free OperationTFTP Trivial File Transfer ProtocolTHL Trans-Hybrid LossTL1 Transaction Language OneTLP Transmission Level PointTLPU Telecommunications Line Protector UnitTLWS Trunk and Line Work StationTIMS Transmission Impairement Measuring SetTIRKS Trunk Integrated Records Keeping SystemTLP Transmission Level PointTMC Time slot Management ChannelTMN Telecommunications Management NetworkTN Telephone NumberTNS Transit Network SelectionTOH Transport OverheadToS Type of ServiceTOS Testing Operation SystemTPDU Transport Protocol Data UnitTPI Tip-Party IdentificationTRA Traffic Restart AllowedTRU Transmit/Receive UnitTRW Traffic Restart WaitingTRX Tandem Repeater ExchangeTSC Test System ControllerTSDU Transport Service Data UnitTSGR Transport System Generic RequirementsTSI Time Slot InterchangeTSID Test Signal IdentificationTSR Terabit Switch RouterTTU Tandem T-1 UnitTX Transmit

U

UA Unnumbered Acknowledgement

UAS Unavailable SecondsUCIC Unequipped Circuit Identification CodeUDC Universal Digital ChannelUDLC Universal Digital Loop CarrierUDP User Datagram ProtocolUI Unit IntervalUI Unnumbered Information (frame)UMTS Universal Mobile Telecommunications SystemUNI User Network InterfaceUNICODE UNIversal trunk-out-of-service CodeUPA User Part AvailableUPC Usage Parameter ControlUPS Uninterruptible Power SystemUPT User Part TestUPU User Oart UnavailableURL Uniform Resource LocatorURL Universal Resource LocatorUSI User System InterfaceUSOC Universal Service Order CodeUSOC Universal Service Ordering CodeUTP Universal Twisted PairUVG Universal Voice-grade Channel Unit

V

V(A) Acknowledge state VariableV(M) Recovery state VariableV(R) Receive state VariableV(S) Sent state VariableVAZO Violating All-Zero OctetVBR Variable Bit RateVC Virtual ChannelVC Virtual CircuitVC Virtual ContainerVCC Virtual Channel ConnectionVCI Virtual Channel IdentifierVCL Virtual Channel LinkVDSL Very high bit rate Digital Subscriber LineVDT Video Dial ToneVG Voice GradeVF Voice FrequencyVLAN Virtual Local Area NetworkVMWI Visual Message Waiting IndicatorVN Virtual NetworkVNS Virtual Network SystemVoATM Voice Over ATMVoB Voice Over BroadbandVOD Video On DemandVoDSL Voice Over DSLVOFDM Vector Orthogonal Frequency Division Multiplexing

VoFR Voice Over Frame RelayVoIP Voice Over Internet ProtocolVOP Voice Over PacketVP Virtual PathVPC Virtual Path ConnectionVPI Virtual Path IdentifierVPN Virtual Private NetworkVPT Virtual Path TerminatorVPX Virtual Path Cross-connectVQC Vector Quantizing CodeVQC Voice Quantizing CodeVQL Vector Quantizing LevelVQL Variable Quantizing LevelVSAT Very Small Aperature SatelliteVSAT Voice over SatelliteVT Virtual TributaryVXML Voice Extensible Markup Language

W

W-DCS Wideband Digital Crossconnect SystemWAN Wide Area NetworkWAN PHY WAN Physical LayerWAP Wireless Application ProtocolWATS Wide Area Telephone ServiceWAW Wide Area WirelessWDCX Wideband and Broadband Digital Cross-connectWDM Wavelength Division MultiplexingWECA Wireless Ethernet Compatibility AllianceWEP Wired Equivalent PrivacyWFA Work Force AdministrationWFQ Weighted Fair QueuingWML Wireless Markup Language

X

XA-FR Exchange Access Frame RelayXA-SMDS Exchange Access Switched Multi-megabit Data ServiceXAME eXchange Access Mapping EntityXC CrossconnectXI X Identification (frame)XID Exchange IdentificationXML Extensible Markup LanguageXO Extended Office

Y

Z

ZBTSI Zero Byte Time Slot InterchangeZCS Zero Code Suppression