Industry Acronyms

Industry Acronyms

23B+D = 23 Bearer + Delta (Channels)
2B+D = 2 Bearer + Delta (Channels)
2W = Two Wire
3 in 24 = 3-in-24 Stress Pattern
4W = Four Wire
A/D = Analog to Digital Conversion
ABC = Airborne Contaminants
AC = Alternating Current
ACF = Access Control Field
ACO = Analog Central Office
ACSE = Association Control Service Element
ADM = Add/Drop Multiplexer
ADTS = Automated Digital Terminal System
ADSL = Asymmetric Digital Subscriber Line
ADSL = Asymmetric Digital Subscriber Line
ADTS = Automated Digital Terminal System
AFI = Authority and Format Identifier
AID = Access Indentifier
AIN = Advanced Intelligent Network
AIS = ALARM Indication signal
AITS = Acknowledged Information Transfer System
ALR = Application Layer Relay
AM = Amplitude Modulation
AMI- Alternate Mark Inversion
AN = Access Node
ANET = Asynchronous NETwork
ANSI = American National Standards Institute
ANSI = American National Standards Institute
APD = Avalanche Photodiode
APS = Automatic Protection Switching
ARDS = AT&T Reference Distribution System
ARF = Amendment Request Form
ASC = Abnormal Station Condition
ASCII = American Standard Code for Informational Interchange
ASE = Application Service Element
ASN.1 = Abstract Syntax Notation 1
AT = Access Tandem
ATLR = Active Transport Layer Relay
ATM = Asynchronous Transfer Mode
ATU-C = ADSL Transmission Unit-Central
ATU-R = ADSL Transmission Unit-Remote
AU = Auxiliary Unit
AU-G = Auxiliary Unit Group
AVD = Alternate Voice Data
AWG = American Wire Gauge
B = Bearer
B3ZS = Bipolar Three Zero Substitution
B6ZS = Bipolar Six Zero Substitution
B8RZ = Bipolar Eight Return-To-Zero
B8ZS = Bipolar Eight Zero Substitution
BCI = Bit Count Integrity
BDCS = Broadband Digital Cross-Connect System
BER = Bit Error Ratio
BERT= Bit Error Rate Test
BIP = Bit Interleaved Parity
BIP-N = Bit Interleaved Parity N
BISDN = Broadband ISDN
Bisyn = Binary Synchronous Communication
BIT = Binary Digit
BITS = Building Integrated Timing Supplies
BLKD = Blocked
BLSR = Bidirectional Line Switched Rings
BNZS = Bipolar Line Code With N Zero Substitution
BOC = Bell Operating Company
BORSCHT = Battery, Over Voltage Prot., Ringing, Signaling, Codec, Hybrid, Test
BPNRZ = Bipolar Non-Return-To-Zero
BPRZ = Bipolar Return-To-Zero
BPV = Bipolar Violation
BRA = Basic Rate Access
BRI = Basic Rate Interface
BRI = Basic Rate Interface
BRZ = Bipolar Return to Zero
BSRF = Basic Synchronization Reference Frequency
CAB = Conformity Assessment Body
CB = Certification Body
CAC = Circuit Access Code
CAP = Competitive Access Provider
CAP = Common Management Information Modulation
CAS = Channel Associated Signaling
CATV = Community Antenna Television (Cable TV)
CBO = Continuous Bit Stream Oriented
CC = Composite Clock
CCC = Clear Channel Capability
CCG = Composite Clock Generator
CCIS = Common Channel Interoffice Signaling
CCITT = International Telegraph & Telephone Consultative Committee
CCM = Customer Control & Management
CCS = Common Channel Signaling
CDU = Clock Distribution Unit
CEPT = European Conference of Post and Telecommunications Administration
CEV = Controlled Environmental Vault
CFA = Carrier Failure Alarm
CGA = Carrier Group Alarm
CID = Craft Interface Device
CID = Calling Address Identification
CLASS = Customized Local Area Signaling Services
CLCI = Common Language Circuit Identification Codes
CLEC = Competitive Local Exchange Carrier
CLEC = Competitive Local Exchange Carrier
CLEI = Common Language EQUIPMENT Identification codes
CLF = Carrier Line Failure
CLFI = Common Language Facility Identification Codes
CLLI = Common Language Location Identification Codes
CLNP = Connectionless-Mode Network Layer Protocol
CLNS = Connectionless Network Service
CLO = Circuit Layout Order
CMI = Control Mode Idle
CMI = Coded Mark Inversion
CMISE = Common Management Information Service Element
CNM = Customer Network Management
CO = Central Office
CODEC = Coder/Decoder
COE = Central Office Equipment
COFA = Change of Frame Alignment
CONP = Connection-Mode Network Layer Protocol
COT = Central Office Terminal
CPE = Customer Premises Equipment
CPU = Central Processing unit
CPN = Customer Premises Node
CR = Clock Recovery
CRC = Cyclic Redundancy Check
CSA = Carrier Serving Area
CSC = Common Signaling Channel
CSMA = Carrier Sense Multiple Access (with collision detection)
CSU = Channel Service Unit
CT = Compliance Testing
CU = Channel Unit
CV = Coding Violation
CW = Continuos Wave
CXR = Carrier
D = Delta (Channel)
D4 = DS1 Level Channel Banks (24 DSO channels)
DA = Distribution Area
D/A = Digital-to-Analog Conversion
DACS = Digital Access and Cross-Connect System
dB = Decibel
dBm = Decible-Milliwatt
dBRN = Decibles Above Reference Noise
DC = Direct Carrier
DCB = Digital Channel Bank
DCC = Data Communications Channel
DCD = Digital Clock Distributor
DCE = Data Communications Equipment
DCN = Data Communications Network
DCO = Digital Central Office
DCS = Digital Cross-connect Systems (software driven; electronic re-route)
DCTF = Digital Cross-connect and Transmission Facility
DDB = Digital Data Bank
DDD = Direct Distance Dialing
DDL = Derived Data Link
DDS = Digital Data System
DDS = Digital Data Services (up to 56kbs)
DF = Distributing Frame
DFB = Distributed Feedback (laser)
DIU = Digital Interface Unit
DLC = Digital Loop Carrier (typically 96 channels on 4/5 T-Cxr lines)
DM = Degraded Minute
DQDB = Distributed Queue Dual Bus
DOC = Declaration of Conformity (EU Directive related to CE Marking)
DR = Digital Rate
DRS = Digital Reference Signal
DS = Digital System
DSL = Digital Subscriber Line
DSLAM = Digital Subscriber Line Access Multiplexer
DS-SMF = Dispersion Shifted Single Mode Fiber
DSAU = Digital Signal Access Unit
DSn = Digital Signal, Level n
DSP = Domain Specific Part
DSU = Data Service Unit
DSX = Digital System Cross-connect
DSX-n = Digital System Cross-connect, Level n
DSX-1 = Digital Signal Cross-connect level 1
DSX-3 = Digital Signal Cross-connect level 3
DS-0 = Digital Signal-Zero
DS0A = Digital Signal, Level 0A
DS0B = Digital Signal, Level 0B
DS0 PTE = Digital Service Level 0 Path Terminating Equipment
DS1 = Digital Signal, Level 1
DS1C = Digital Signal, Level 1C
DS2 = Digital Signal, Level 2
DS3 = Digital Signal, Level 3
DTAU = Digital Test Access Unit
DTE = Data Terminal Equipment
DTF = Digital Transmission Facility
DTMF = Dual Tone Multifrequency Signaling
DTR = Data Terminal Ready
DUV = Data Under Voice
DWDM = Dense Wave Division Multiplexing (multiple wavelengths on a fiber)
EC = Echo Canceller
EC = Error Correction
ECSA = Exchange Carrier Standards Association
EDSX = Electronic Digital Signal Cross-Connect System
EE = Engineering Evaluation
EER = Engineering Evaluation Report
EFS = Error Free Second
EIA = Electronics Industries Association
ELED = Edge Emitting LED
EMR = Electro Magnetic Radiation
EMC = Electro-Magnetic Compatibility
EMEA = European Middle East Africa.
EO = End Office
EOC = Embedded Operations Channel
EOW = Express Orderwire
E/O = Electrical/Optical Conversion
EQTV = Enhanced/Extended Quality Television
E&M = Ear & Mouth
ERL = Echo Return Loss
ES = End System
ES = Errored Second
ESF = Extended Superframe Format
ESL = Environmental Simulation Laboratory
ESS = Electronic Switching System
ET = Exchange Termination
ETSI – European Telecommunications Standards Institute
EU = European Union
EUT = Equipment Under Test
FAS = Frame Alignment Signal
FAD = Facility Access DiGroup
F-Bits = Frame Bits
FC = Field Evaluation
FCC = Federal Communications Commission
FDF = Fiber Distribution Frame
FDI = Feeder Distribution Interface
FDDI = Fiber Distributed Data Interface
FDF = Fiber Distribution Frame
FDI = Feeder Distribution Interface
FDL = Facility Data Link
FDM = Frequency-Division Multiplex
FE = Far End
FEBE = Far End Block Error
FEC = Forward Error Correction
FEP = Front End Processor
FERF = Far End Receive Failure
FEV = Far-End Voice
FIT = Failure In Time
FITL = Fiber In The Loop
FM = Frequency Modulation
FMAC = Facility Maintenance and Administration Center
FOTS = Fiber optic Transmission System
FPS = Framing Pattern Sequence
FS = Forced Switch
FSK = Frequency Shift Keying
FT = File Transfer
FTAM = File Transfer and Access Management
FTC = Federal Trade Commission
FTTC = Fiber To The Curb
FTTH = Fiber To The House
FTTN = Fiber To The Neighborhood
FWHM = Full Width Half Maximum
FX = Foreign Exchange
GHz = Giga-Hertz
GNE = Gateway Network Element
GOI = Generic Operations Interface
GOSIP = (US) Government OSI Profile
GPS = Global Positioning System
GR = Generic Requirements (i.e. GR-63-CORE)
GUI = Graphical User Interface
H11 = Bearer Channel – 1536 kb/s
HCDS = High Capacity Digital Service
HCS = Header Check Sequence
HDB3 = High Density Binary 3
HDLC = High Level Data Link Control
HDSL = High-bit-rate Digital Subscriber Line
HDT = Host Digital Terminal
HDTV = High Definition Television
HE = Head End
HECI = Human-interface Equipment Catalog Item
HECIG = Human-interface Equipment Catalog Item Group
HFC = Hybrid-Fiber Coaxial Cable
HiCap = High-Capacity Digital Service (aka HCDS)
HO = Bearer Channel – 384 kb/s
I-ADM = Intermediate Add/Drop Multiplex
IAO = Intraoffice
IC = Industry Canada
IC = Interexchange Carrier/Inter-Lata Carrier
IDF = Intermediate Distributing Frame
IDI = Initial Domain Identifier
IDLC = Integrated Digital Loop Carrier
IDP = Initial Domain Part
IDT = Integrated Digital Interface Terminal
IEC = Interexchange Carrier
IF = Intermediate Frequency
IFC = Initial First Cost
ILEC = Incumbent Local Exchange Carrier
ILEC = Incumbent Local Exchange Carrier
INE = Intelligent Network Element
IP = Internet Protocol
IR = Intermediate Reach
IS = Intermediate System
ISCP = Integrated Service Control Point
ISDN = Integrated Services Digital Network
ISDN = Integrated Services Digital Network
ISI = Intersymbol Interface
ISMX = Intergrated Subrate Multiplexer
ISO – International Standards Organization
ISO = International Standards Organization
ISP = Internet service Provider
ITE = Information Technology Equipment
ITU-T = International Telecommunications Union – Telecommunications
IVR = Interactive Voice Response
IWU = Interworking Unit
IXC = Inter-exchange Carrier
KA = Keep Alive Signal
Kb/s = Kilo Bits/Second
LAN = Local Area Network
LAPB = Link Access Procedure Balanced
LAPD = Link Access Procedure Balanced on th e D Channel
LAPD+ = Link Access Procedure for non-D Channel (applications)
LASER = Light Amplification of Stimulated Emission of Radiation
LATA = Local Access and Transport Area
LBC = Laser Bias Current
LBE =  Loopback Enable
LBO = Line Build Out
LCN = Local Communications Network
LDS = Local Digital Switch
LEC = Local Exchange Carrier
LED = Light Emitting Diode
LEIM = Loop Electronics Inventory Module
LEN = Local Exchange Node
LID = Local Injection Detection
LIU = Line Interface Unit
LLB = Latching Loopback
LLC = Link Layer Control
LLDL = Low Level Data Link
LMOS = Loop Maintenance Operations Systems
LOC = Letter of Compliance
LOF = Loss Of Frame
LOFA = Loss OF Frame Alignment
LOH = Line Overhead
LOP = Loss Of Pointer
LORAN-C = Long Range Navigation Radio Communications
LOS = Loss Of Signal
LOW = Local Orderwire
LP = Low Pass
LR= Long Reach
LSB = Least Significant BIT
LSC = Loopback Select Code
LSI = Large Scale Integration
LSS = Link Status Signal
LT = Lata Tandem
LTE = Line Terminating Equipment
LTR = Lunch Time Review
M RMS PI = Maximum RMS Phase Instability
M13 = DS1 to Ds3 Multiplexer
MA = MJU Alert
MAC = Media Access Control
MAN = Metropolitan Area Network
Mb/s = Mega bits/second
MD = Mediation Device
MDF = Main Distributing Frame
MF = Mediation Function
MF = Multifrequency
MFJ = Modification of Final Judgement
MHZ = Mega Hertz
MIB = Management Information Base
MJU = Multipoint Junction Unit
MLM = Multiongitudinal Mode
MLT = Mechanized Loop Testing
MML = Human-Machine Language
MOC = Management Operation Channel
MOS = MUX Out of Sync.
MPN = Modal Partition Noise
MS = Manual Switch
MSB = Most Significant BIT
MSO = Multiple Service Operator
MTAU = Metallic Test Access Unit
MTBF = Mean Time Between Failures
MTIE = Maximum Time Interval Error
MTS = Message Telecommunication Service
MTSO = Mobile Telephone Switching Office (cellular provider’s switching center)
MTTR = Mean Time To Repair
MU = Multipoint Unit
MUX = Mulitplexer
MX3 = Multiplexer (X-Low Speed, DS3 High Speed)
NAVSTAR = Global Positioning System
NCB = National Certification Body
NCTE = Network Channel Terminating Equipment
NDF = New Data Flag
NE = Network Element
NEBS = Network Element – Building System
NEBS = Network Equipment Building Standard
NEBS = Network Equipment Building Systems
NEs = Network Elements (equipment)
NESC = National Electrical Safety Code
NGDLC = Next Generation Digital Loop Carrier
NGS = Next Generation Switch
NI = Network Interface (physical point of separation between network and CPE)
NIC = Network Interface Card
NIST = National Institute for Standards & Technology
NIU = Network Interface Unit (aka Smartjack)
NLSS = Non-Locally Switched Services
NMA = Network Monitoring and Analysis
NMS = Network Management System
NNI = Network Node Interface
NOC = Network Operations Center
NPA = Numbering Plan Area
NPDU = Network Protocol Data Unit
NRC = Network Reliability Center
NRTL = National Recognized Testing Laboratory
NRZ = Non-Return-To-Zero
NSA = Non-Service Affecting
NSAP = Network Service Access Point
NSPDU = Network Service Protocol Data Unit
NT = Network Termination
NT1 = Network Termination 1
NT2 = Network Termination 2
NTEC = Network Terminal Equipment Center
NTSC = National Television Systems Committee
O/E = Optical/Electrical Conversion
OADM = Optical Add-Drop Multiplexer
OAM & P = Operations, Administration, Maintenance & Provisioning
OATS – Open Air Test Site
OC = Optical Carrier
OC-1 = Optical Carrier Level 1
OC-N = Optical Carrier Level N
OC-n = SONET Optical Carrier signal rate
OCRF = Optical Cable Rearrangement Facility
OCU = Office Channel Unit
OCU-DP = Office Channel Unit-Data Port
OcuSpan = Telcordia’s Remote, End-to-End Testing Operations system
ODC = Optical Directional Coupler
ODSX = Optical Digital Signal Cross-Connect
OEIC = Opto-Electronic Integrated Circuit
OEM = Original Equipment Manufacturer
OH- Overhead
OIM = Operations Interface Module
ONA = Open Network Architecture
ONE = Optical Network Element
ONU = Optical Network Unit
OOF = Out OF Frame
OOS = Out Of Service
OPR = Optical Power Received
OPS/INE = Operation Process System/Intelligent Network Elements
ORB = Office Repeater Bay
ORL = Optical Return Loss
OS = Operation Systems
OSA = Optical Serving Areas
OSC = Optical Supervisory System
OSHA = Occupational Safety & Health Administration
OSI = Open System Interconnection
OSP = Outside Plant (Distribution of Loop)
OSS = Operational Support System
OTGR = Operations Technology Generic Requirements
OTM = Optical Terminal Multiplexer
OW = Orderwire
OX = Optical Cross-Connect
PAD = Packet Assembly/Disassembly
PAM = Pulse Amplitude Modulation
PAR = Project Amendment Request
PBX = Private Branch Exchange
PCA = Project Change Authorization
PBX = Private Branch Exchange
PCM = Pulse Code Modulation
PDH = Plesiochronous Digital Hierarchy
PDN = Passive Distribution Network
PDU = Protocol Data Unit
PDV = Pulse Density Violation
PFOC = Passive Fiber Optic Components
PID = Private Identification
PIN = Personal Identification Number
PIN = Positive Intrinsic Negative (photodiode)
PIU = Plug-in Unit
PJ = Pointer Justification
PJC = Pointer Justification Counter
PLCP = Physical Layer Convergence
PM = Performance Monitoring
PMD = Polarization Mode Dispersion
POH = Path Overhead
PONs = Passive Optical Networks
POP = Point of Presence
POT = Point of Termination
POTS = Plain Old Telephone Service
POTS = Plain Old Telephone Service
PPDU = Presentation Protocol Data Unit
PPM = Pulse Position Modulation
PRA = Primary Rate Access
PRC = Primary Reference Clock
PRF = Primary Reference Frequency
PRI = Primary Rate Interface
PRI = Primary Rate Interface
PRS = Primary Reference Source
PSAP = Presentation Service Access Point
PSC = Protection Switching Count
PSD = Protection Switching Duration
PSDN = Public Switched Data Network
PSDS = Public Switched Digital Service
PSK = Phase Shift Keying
PSN = Packet Switched Network
PSTN = Public Switched Telephone Network
PT = Performance Testing
PTE = Path Terminating Equipment
PTF = Path Terminating Function
PTO = Public Telephone Operator
PUB = Publication
PV = Pointer Value
PVC = Permanent Virtual Circuit
PVC = Private Virtual Circuit
QAM = Quadrature Amplitude Modulation
QFI = Quarterly Follow-Up Inspection
QoS = Quality of Service
QRS = Quasi-Random Signal
QRSS = Quasi-Random Signal Source
RADSL = Rate Adaptive Digital Subscriber Line
RAM = Random Access Memory
RBOC = Regional Bell Operating Company
RBOC = Regional Bell Operating Company
RDL = Remote Digital Loop
RDT = Remote Digital Terminal
RF = Radio Frequency
RFI = Radio Frequency Interface
RFP = Request For Proposal
RFQ = Request for Quotation
RGTR = SONET Regenerator
RJ11 = Registered Jack Standard- 11
RJ14 = Registered Jack Standard-14
RJ45 = Registered Jack Standard-45
RJ48C = Registered Jack Standard-48C
RMN = Remote Multiplexer Node
RMS PI = RMS Phase Instability
ROM = Read-Only Memory
RPP = Reliability Prediction Procedure
RS-232 = Registered Standard-232
RSS = Remote Switching System
RSU = Remote Switching Unit
RT = Remote Terminal
RTAP = Remote Test Access Point
RTP = Remote Test Panel
RTS = Remote Testing System
Rx = Receive
RZ = Return to Zero
SA = Service Affecting
SAI = Serving Area Interface (200-600 living units)
SAP = Service Access Point
SAPI = Service Access Point Indentifier
SARTS = Switched Access Remote Testing System
SCC = Standards Council of Canada
SCC = Switching Control Center
SCIU = Synchronous Clock Insertion Unit
SCP = Service Control Point
SD = Signal Degrade
SDH = Synchronous Digital Hierarchy (European SONET standard)
SDSL = Symmetric Digital Subscriber Line
SEAS = Signaling Engineering and Administration System
SEFS = Severely Errored Framing Second
SES = Severely Errored Second
SESs = Severely Errored Seconds
SF = Signal Fail
SF = Single-Frequency Signaling
SF = Superframe Format
SL = System Letter
SLC-96 = Subscriber Loop Carrier-96
SLED = Surface Emitting LED
SLIM = Subscriber Loop Interface Module
SLM = Single Lomgitudinal-Mode
SMAS = Switched Maintenance Access System
SMCU = System Management Unit
SMDS = Switched Multimegabit Data Service
SMF = Single Mode Fiber
SMOLTS = Single Mode Optical Loss Test Set
SMS = Service Management System
SMS = Switched Multimegabit Service
SMU = synchronization Monitoring Unit
SMU = System Management Unit
SNDCF = Subnetwork Dependent Convergence Function
SNMP = Simple Network Management Protocol
SNMP = Simple Network Management Protocol
SNR = Signal to Noise Ratio
SOH = Section Overhead
SONET = Synchronous Optical Network
SONET ADM = Synchronous Optical Network Add-Drop Multiplex
SPC = Stored Program Control
SPE = Synchronous Payload Envelope
SR = Short Reach
SR = Special Report
SR = Special Report (i.e. SR-3580)
SRD = Synchronization Reference Distributor
SRDC = Sub-Rate Digital Cross Connect
SRDM = Sub-Rate Digital Multiplexer
SRM = Sub-Rate Multiplexing
SS7 = Signaling System 7
SSC = Special Service Center
SSP = Service Switching Point
SSR = Side-Mode Suppression Ratio
STB = Set Top Box
STE = Section Terminating Equipment
STM = Synchronous Transport Mode
STP = Signal Transfer Point
STS = Synchronous Transport Signal
STS POH = STS Path Overhead
STS PTE = STS Path Terminating Equipment
STS PTE = STS Synchronous Payload Envelope
STS-1 = Synchronous Transport Signal Level 1
STS-N = Synchronous Transport Signal Level N
STS-Nc = Concatenated Synchronous Transport Signal Level N
SVC = Switched Virtual Circuit
SYNTRAN = Synchronous (DS3) Transmission
T & R = Tip and Ring
T1ASU = T1 Automatic Switching Unit
T1DM = T1 Data Multiplxer
TA = Technical Advisory
TA = Terminal Adapter
TA = Test Alert
TAG = Technical Advisory Group
TASC = Telecommunications Alarm Surveillance and Control
TBD = To Be Determined
TBOS = Telemetry Byte Oriented Serial
TC = Toll Center
TCA = Threshold Crossing Alert
TCB = Telecommunications Certification Body
TCP/IP = Transmission Control Protocol/Internet Protocol
T-Cxr = T Carrier (DS1 Level Copper Transport; 24 Channels)
TDM = Time Division Multiplex
TDMA = Time Division Multiple Access
TDN = Time Division Network
TE = Terminal Equipment
TEN = Transit Exchange Node
TIA = Telecommunications Industries Association
TIC = T-Carrier-Digital Transmission System (48 Channels)
TICL = Temperature Induced Cable Loss
TID = Target Identification
TIE = Time Interval Error
TIP = Transition in Progress
TIRKS = Trunk Integrated Record Keeping System
TL1 = Transaction Language 1
TLP = Transmission Level Point
TM = Technical Memorandum
TM = Terminal Multiplex
TMN = Telecommunications Management Network
TMS = Time Multiplexed Switch
TOH = Transport Overhead
TP = Transport Protocol
TP4 = Transport Protocol Class 4
TPF2 = Transaction Processing Full conformance stack #2
TPM1 = Transaction Processing using TL1 over CCITT X.25
TR = Technical Reference-Requirements
TR = Technical Requirement (i.e. TR- )
TSA = Timeslot Assignment
TSG = Timing Signal Generator
TSGR = Transport System Generic Requirements
TSI = Time Slot Interchanger
TU = Tributary Unit
TUG = Tributary Unit Group
Tx = Transmit
UAS = Unavailable Second
UDC = Universal Digital Channel
UDLC = Universal Digital Loop Carrier
UDP = User Datagram Protocol
UI = Unit Interval
UID = User Identification
UITS = Unacknowledged Information Transfer Service
UMC = Unassigned MUX Channel
UNI = User Network Interface
UP = Micro Processor
UPSR = Unidirectional Path Switched Ring
USL = User System Language
UTC = Universal Time Coordinated
UTP = Unshielded Twisted Pair
UVG = Universal Voice Grade
V5 = VT Path Overhead
VC = Virtual Circuit
VC = Virtual Container
VCI = Virtual Channel Identifier
VDSL = Very High Bit Rate Digital Subscriber Line
VDT = Video Display Terminal
VDT = Visual Display Terminal
VF = Voice Frequency
VLSI = Very Large Scale Integration (or Integrated Circuit)
VoIP = Voice Over Internet Protocol
VT = Virtual Tributary
VT 1.5 = Virtual Tributary 1.5
VT PTE = VT Path Terminating Equipment
VT SPE = VT Synchronous Payload Envelope
VTx = Virtual Tributary of size “x”
VTx-Nc = Concatenated Virtual Tributary
WAN = Wide Area Network
WDCS = Wideband Digital Cross-connect System
WDM = Wavelength Division Multiplexing
WS = Workstation
WTR = Wait To Restore
WWW = World Wide Wen
XDSL = High-speed Digital Subscriber Line services/equipment (e.g. ADSL)
YEL = Yellow Alarm
ZBTSI = Zero Byte Time Slot Interchanger
ZCS = Zero Code Suppression