Acronyms

Acronyms (and abbreviations)

Note: In general this list does not include company names (e.g. AT&T, HP) and with a few notable exceptions (e.g. SNA) does not include proprietary protocols or products (e.g. EWSD) etc.

NUMBERS

1ESS (electronic switching system No 1)
2B1Q (2 binary, 1 quaternary line code)
2G (second generation - esp 2G mobile digital system)
2W (two-wire)
3DES (a data encryption standard with 3 keys)
3G (third generation mobile)
3GPP (third generation mobile). External web-site
3GPP2 (third generation partnership project 2 - USA). External web-site.
4ESS (electronic switching system No 4)
4B3T (4 binary, 3 ternary line code)
4W (four-wire)
5ESS (electronic switching system No 5)
6B4T (6 binary, 4 ternary line code)
6PE (IPv6 provider edge router)
8PSK
10BASE-T (10 Mbit/s Ethernet over twisted pair)
10GEA (10 Gigabit Ethernet Alliance). External web-site.
16QAM
24 x 7 (24 hours a day, 7 days a week)
100BASE-T (100 Mbit/s Ethernet - Fast Ethernet)
112 (European-wide emergency number)
802 (IEEE standards for Ethernet, including wireless versions)
911(USA emergency number)
999 (UK emergency number - in addition to 112)
1394 (IEEE high-speed bus also known as Firewire)

AAA (authorisation, authentication and accounting)
AAB (automatic alternative billing)
AAC (advanced audio coding - a part of MPEG4)
AAL (asynchronous transfer mode adaptation layer)
AAR (allocating access router)
ABD (abbreviated dialling)
ABR (area border router)
ABR (available bit rate)
ABS (alternative billing service)
AC (alternating current)
AC (authentication centre)
ACC (account card calling)
ACD (automatic call distribution)
ACELP (adaptive code excited linear prediction)
ACIF (Australian Communications Industry Forum)
ACK (acknowledgement) - a contraction, not an acronym.
ACM (address complete message)
ACM (Association of Computing Machinery)
ACPI (advanced configuration and power interface)
ACR (actual cell rate)
ACSE (association control service element)
ACTA (Administrative Council for terminal Attachments [USA]). External web-site.
ACTIUS (Association of Computer Telephone Integration Users and Suppliers).
ACTS (Advance Communications Technology and Services - a European initiative)
A/D (analogue to digital)
ADC (advise duration and charge)
ADC (analogue-to-digital converter)
ADCCP (advanced data communication control procedure)
ADM (adaptive data modulation)
ADM (add-drop multiplexer)
ADPCM (adaptive differential pulse code modulation)
ADPN (administration data packet network)
ADSI (analogue display service interface)
ADSL (asymmetric digital subscriber line)
ADSLF (ADSL Forum) - see DSL Forum
AEA (American Electronics Association). External web site.
AES (advanced encryption standard)
AES (Audio Engineering Society). External web site.
AFR (automatic face recognition)
AFRINIC (African Network Information Centre). External web site.
AGC (automatic gain control)
AGCH (access grant channel)
AH (authentication header)
AHCIET (Association of Latin American R&D and Telecommunications companies). External web site - Spanish.
AI (artificial intelligence)
AIIM (Association for Information and Management). External web site.
AIN (advanced intelligent network)
AINI (ATM internetwork interface)
AIS (accept into service)
AKA (authentication and key agreement)
ALC (active level control)
ALC (automatic level control)
ALTS (Association for Local Telecommunications Services)
AM (amplitude modulation)
AMF (Asian Multimedia Forum).
AMF (authentication management field)
AMI (alternate mark inversion)
AMLCD (active matrix liquid crystal display)
AMR (adaptive multi-rate)
AMPS (advanced mobile phone system)
ANI (automatic number identification)
ANS (advanced networks and services)
ANSI (American National Standards Institute). External web-site.
AoA (angle of arrival)
AO/DI (always on dynamic ISDN)
AODV (ad-hoc on-demand distance vector - routing protocol for ad-hoc networks)
AOEMA (Asia Oceania Electronic Marketplace Association). External web site.
AOW (Asia Oceania Workshop)
AP (access point)
AP (action point)
APCO (Association of Public-safety Commission Officials). External web site.
APD (avalanche photo diode)
API (application programming interface)
APPI (Advanced Peer to Peer Interworking forum)
APON (ATM passive optical network)
APNIC (Asia Pacific Network Information Centre)
AR (access router)
ARFCN (absolute radio frequency channel number)
ARIB (Association of Radio Industries and Businesses - Japan). External web site.
ARIN (American Registry for Internet Numbers). External web site.
ARP (address resolution protocol)
ARPANET (Advanced Research Projects Agency network)
ARPK (administrator root public key)
ARPU (average revenue per user)
ARQ (automatic repeat request)
AS (application server)
AS (authentication server)
AS (autonomous system)
ASBR (autonomous system boundary routing)
ASCII (American standard code for information exchange)
ASDH (access synchronous digital hierarchy)
ASEP (average symbol error probability)
ASIC (application specific integrated circuit)
ASK (amplitude shift keying)
ASLA (application service level ageements)
ASN 1 (abstract syntax notation number 1)
ASN (autonomous system number)
ASO (Address Supporting Organisation). External web site.
ASON (automatically switched optical network)
ASP (applications service part) - SS7
ASP (applications service provider)
ASPIC (Application Service Provider Industry Forum)
ASR (automatic speech recognition)
ATIS (Alliance for Telecommunications Industry Solutions). External web-site.
ATM (asynchronous transfer mode)
ATMP (ascend tunnel management protocol)
ATMF (ATM forum). External web site.
AU (administation unit) - in STM1 frame
AUI (attachment user interface - Ethernet)
AUP (acceptable use policy)
AUTN (authentication token)
AV (authentication vector)
A/V (audi o/visual)
AVC (automatic volume control)
AVL (automatic vehicle location)
AWG (American wire gauge)
AWG (arrayed waveguide gratings)
AWGN (additive white Gaussian noise)
AXE (automatic exchange equipment - Ericsson)

B2B (business to business)
B2C (business to consumer/customer)
B2E (business to employee)
B2G (business to government)
B8ZS (bipolar with 8 zero substitution)
BAS (broadband access server)
BB (broadband)
BBM (break before make)
BCC (block check character)
BCCH (broadcast control channel)
BCCS (bearer channel control signalling)
BCD (binary coded decimal)
BCF (base-station control function)
BCM (basic call model)
BCSM (basic call state machine/model)
BDM (bit demodulator)
BECN (backward error congestion notification)
BER (bit error rate)
BFI (bad frame indication)
BG (border gateway)
BGCF (breakout gateway control function)
BGP (border gateway protocol)
BHCA (busy hour call attempt[s])
BICC (bearer independent call-control)
BIOS (basic input/output system)
B-ISDN (broadband integrated services digital network)
BISUP (broadband integrated services user part) - SS7
BIWF (bearer interworking function)
BJT (bipolar junction transistor)
BLIP (background limited infrared performance)
BLSR (bidirectional line-switched rings)
BMC (broadcast/multicast control)
BNC (a bayonet-locking co-axial connector - origin of 'NC' disputed)
BOC (Bell operating company)
BORSCHT (battery feed; overvoltage protection; ringing; supervision; coding and decoding;hybrid; testing)
BPEL (business process execution language)
BPF (band-pass filter)
BPI (baseline privacy)
BPMI (Business Process Management Initiative)
BPO (business process outsourcing)
BPON (broadband passive optical network)
BPR (business process re-engineering)
BPSK (binary phase shift keying)
BRA (basic rate access)
BRAIN (broadband radio access for IP-based networks)
BRAN (broadband radio access networks)
BRAS (broadband registration, admission and status)
BRAS (broadband remote access server)
BRI (basic rate ISDN)
BS (base station)
BS (bearer service)
BSC (base station controller)
BSD (Berkeley System Distribution - a version of UNIX developed by the University of California at Berkeley)
BSI (British Standards Institute). External web-site.
BSIC (base station identity code)
BSS (base station [sub]system)
BSS (basic service set)
BSSAP (base station application part)
BSSMAP (base station management application part)
BTA (Broadcasting Technology Association) - now part of ARIB
BTS (base transceiver station)
BUS (broadcast unknown server)
BVA (billing validation application)
BW (bandwidth)
BWA (broadband wireless access)
BWIF (Broadband Internet Wireless Forum). External web site.
B-WLL (broadband wireless local-loop)

C2 (command and control)
C3i (command, control, communications and information systems)
C4ISR (command, control, communications, computers, intelligence, surveillance and reconnaissance)
C7 (ITU - was CCITT - signalling system number 7)
CA (certification authority)
CA (conditional access [in DRM])
CAC (connection admission control)
CAD (computer aided design)
CAGR (compound annual growth rate)
CAI (common air interface)
CAM (computer aided manufacturing)
CAMP (core assisted mesh protocol)
CAR (committed access rate)
CASE (computer-aided software engineering)
CAMEL (customised application for mobile network enhanced logic)
CAP (CAMEL application part)
CBCH (cell broadcast channel)
CBOP (Consortium for Business Object Promotion - Japan). External web site - Japanese.
CBR (constant bit rate)
CBR (constraint based routing)
CBT (computer based training)
CC (call control)
CCAF (call control agent function)
CCAMP (common control and management protocols)
CCBS (completion of call to busy subscriber)
CCC (command, control and communications)
CCC (credit card calling)
CCCH (common control channel)
CCD (charge coupled device)
CCF (call-control function)
CCK (common cipher key)
CCS (common channel signalling)
CCS (100 call seconds: 36 CCS = 1 Erlang)
CCS (hundreds of call seconds)
CCSK (cyclical code shift keying)
CCITT (In French = International Telegraph and Telephone Consultative Committee -archaic: now ITU-T)
CCIR (In French = International Radio Consultative Committee - archaic: now ITU-R)
CCM (certificate configuration message)
CD (call distribution)
CD (committee draft)
CD (compact disc)
CDGPS (code division generalised processor sharing)
CDN (content distribution network)
CDR (call detail record)
CDR (charging data record)
CDMA (code division multiple access)
CDMA 2000 (a proprietary version of 3G code division multiple access)
CDPD (cellular digital packet radio)
CDV (cell delay variation)
CDVCC (coded digital verification colour code)
CELP (card edge low profile)
CELP (code excited linear predictive coding)
CEN (In French - European Committee for Standardisation - counterpart to ISO). External web-site.
CENELEC (In French - European Committee for Electrotechnical Standards). External web-site.
Centrex (central office exchange - providing PBX-like services)
CEO (chief executive officer)
CEPT (Conference of European Postal and Telecommunications Administrations). External web-site.
CER (cell error ratio)
CERN (European Organisation for Nuclear research). External web site.
CERT (computer emergency response team)
CESG (Communications-Electronics Security Group - UK). External web site.
CEV (controlled environment vault)
CF (call forward)
CFO (chief financial officer)
CGA (colour graphics adapter)
CGI (common gateway interface)
CHTML (compact hypertext markup language)
CIC (circuit identification code)
CIDR (classless internet domain routing)
CIGR (classless limited device configuration)
CIO (chief information officer)
CIR (channel impulse response)
CIR ( committed information rate)
CIRT (computer incident response team)
CISC (complex instruction set computers)
CIX (Commercial Internet Exchange)
CK (cipher key)
CLASS (customer-calling local area signalling system - USA)
CLC (Carrier Liaison Committee)
CLEC (competitive local exchange carrier)
CLI (calling line identity)
CLIP (calling line identification, presentation)
CLIR (calling line identification, restriction)
CLNP (connectionless network protocol)
CLP (cell loss priority)
CLR (cell loss ratio)
CLUT (colour look-up table)
CM (configuration management/manager)
CMIP (common management interface protocol)
CMOS (complementary metal-oxide semiconductor)
CMR (cell misinsertion rate)
CMS (call management server)
CMSS (call management server signalling)
CMTS (cable modem terminating system)
CMYK (cyan, magenta, yellow, black)
CN (core network)
CNI (co-operative networking architecture)
CNI (critical national infrastructure)
CNR (combat net radio)
CO (central office)
codec (coder/decoder)
COIN (community of interest network)
COLP (connected line identification, presentation
COLR (connected line identification, restriction)
COM (common object model)
COO (chief operating officer)
COPS (common open policy service)
CORBA (common object request broker architecture)
CORE (Council of Registrars). External web site.
COTS (commercial off the shelf)
CoS (class of service)
CP (certificate policy)
CPCS (common part convergence sublayer)
CPE (customer premises equipment)
CPEX (Customer Profile Exchange). External web-site.
CPFSK (continuous phase frequency shift keying)
CPI (common part indicator)
CPL (call processing language)
CPM (continuous phase modulation)
CP/M (control programme for microcomputers)
CPMS (cost per Megabit shipped)
CPP (calling party pays)
CPPM (content protection for pre-recorded media [DVD-A])
CPRM (content protection for recordable media [DVD-A])
CPS (certificate practices statement)
CPS (call processing system)
CPS (carrier pre-select)
CPS (characters per second)
CPU (central processing unit)
CR (cell relay)
CR (cognitive radio)
CRC (cyclic redundancy checking)
CRD (customer requirement definition)
CRL (certificate revocation list)
CR-LDP (constraint routed - label distribution protocol)
CRM (customer relationship management)
CRS (certificate request syntax)
CRT (cathode ray tube)
CRV (call reference value)
CS (call server)
CS (circuit switched/switching)
CS (convergence sub-layer)
CS1, CS2 etc (capability sets 1, 2, etc for intelligent network)
CSCF (call session control function)
CSCF (call state control function)
CSD (circuit switched data - also HSCSD)
CSE (CAMEL service environment)
CSF (call serving function)
CSMA (carrier sense multiple access)
CSMA/CA (CSMA with collision avoidance)
CSMA/CD (CSMA with collision detection)
CSP (communication service provider)
CSR (certificate signing request)
CSS (customer service system - UK - BT)
CSTA (computer supported telephony applications - the ECMA standard for CTI)
CT (cordless telephone, CT1, CT2 etc)
CTD (cell transfer delay)
CTFJ (Computer Telephony Forum of Japan). External web site.
CTI (computer telephony integration)
CTL (certificate trust list)
CTO (chief technology officer)
CUG (closed user group)
CVD (chemical vapour deposition)
CVDT (cell variation delay tolerance)
CVSD (continuously variable slope delta)
CW (carrier wave or continuous wave)
CWTS (Chinese Wireless Telecommunications Standard group). External web site.

DA (destination address)
DAB (digital audio broadcasting)
DAFS (direct access file system)
DAI (digital audio interface)
D-AMPS (digital advanced mobile phone system) OR dual-mode AMPS?????
DARPA (Defense Advanced Research Projects Agency). External web-site.
DAS (digital archiving server)
DAS (directly attached storage)
DAT (digital audio tape)
DAVIC (Digital Audio-Video Council). External web site.
dB (decibel)
DBA (dynamic bandwidth allocation)
DBMS (database management system)
DBS (direct broadcast satellite)
DBTMA (dual busy tone multiple access)
DC (direct current)
DCA (Defense Communications Agency - USA)
DCCH (dedicated control channels)
DCE (digital computing environment)
DCE (data circuit-terminating equipment)
DCF (discounted cash flow)
DCF (disengage confirm)
DCK (derived cipher key)
DCMI (Dublin Core Metadata Initiative). External web site.
DCML (data centre mark-up language)
DCOM (distributed component object module)
DCR (dynamic controlled routing)
DCT (discrete cosine transformation)
DCOM (distributed component object model)
DCS (digital cellular system) e.g. DCS 1800
DDI (direct dialling in)
DDoS (distributed denial of service)
DDR-SDRAM (double data rate - synchronous dynamic random access memory)
DDS (direct digital synthesiser)
DDSN (digital derived services network - UK)
DECT (digital enhanced cordless telecommunications)
DEN (directory enabled network)
DES (data encryption standard)
DF (direction finding)
DFB (distributed feedback [laser])
DFCA (???????????????) Nokia in Bangalore
DFE (decision feedback equalizer)
DFE (departure from estimate)
DFE (digital front end)
DFT (discrete Fourier transform)
DG (Director/Directorate General)
DHCP (dynamic host configuration protocol)
DID (direct inward dialling)
DIMM (dual in-line memory module)
DIS (draft international standard)
DLC (digital loop carrier)
DLCI (data link connection identifier)
DLE (digital link escape)
DLE (digital local exchange)
DLEC (data competitive local exchange carrier)
DLL (digital link library)
DLTU (digital line trunk unit, also digital line terminating unit)
DM (delta modulation)
DMA (direct memory access)
DMSP (distributed mail system protocol)
DMSU (digital main switching unit - UK)
DMT (discrete multi-tone - ADSL transmission method)
DMTF (Distributed Management Task Force Inc). External web site.
DN (directory number = telephone number)
DNA (digital network architecture - Digital Equipment Corporation)
DNIS (dialled number information string)
DNL (differential non-linearity)
DNS (domain name system/server/service)
DOCSIS (data over cable service interface specification)
DoD (Department of Defense [USA])
DoD (downstream on demand)
DOI (digital object identifier [DRM]). External web site.
DOPG (The Distributed Object Promotion Group - Japan). External web site.
DoS (denial of service)
DOS (disc operating system used by Microsoft)
DP (detection point)
DP (dial pulse)
DP (distribution point)
DPC (destination point code)
DPCM (differential pulse code modulation)
DPCN (digital private circuit network)
DPD (delegated path discovery)
DPE (distributed processing environment)
DPI (deep packet inspection)
DPNSS (digital private network signalling system)
DPSK (differential phase shift keying)
DPT (dynamic packet transport)
DPV (delegated path verification)
DQ (directory enquiries)
DQDB (distributed queue dual bus)
DQPSK (differential quadrature phase shift keying)
DR (digital radio)
DRA (distributed Raman amplification)
DRAM (dynamic random access memory)
DREL (digital rights expression language)
DRM (digital rights management)
DRQ (disengage request)
DS (differentiated services)
DS (direct sequence)
DS (distribution system)
DS1 etc (digital signal [hierarchy])
DSCP (DiffServ code point)
DSDV (destination sequenced distance vector)
DSL (digital subscriber loop/line)
DSLAM (digital subscriber loop access multiplexer)
DSMA (digital sense multiple access)
DSML (directory services markup language)
DSN (defence switched network - US)
DSN (derived services network - UK)
DSP (digital signal processing)
DSR (dynamic source routing [protocol])
DSS (digital signature standard)
DSS1 (digital subscriber system No 1 - UK)
DSSS (direct sequence spread spectrum)
DSV (dynamic signature verification)
DTAP (digital transfer application part)
DTC (digital traffic channel)
DTE (data terminal equipment)
DTH (direct to home)
DTL (diode transistor logic)
DTM (dynamic synchronous transfer mode)
DTM (dynamic traffic management)
DTMF (dual-tone multi-frequency)
DTP (desktop publishing)
DTPM (distributed transaction processing monitor)
DTX (discontinuous transmission)
DU (downstream unsolicited)
DUT (device under test)
DVB (digital video broadcasting with C [cable], H [handheld], S [satellite] and T [terrestrial] variants). Also a specification organisation - external web-site.
DVD (digital versatile disk)
DVI (digital video interface)
DVMRP (distance vector multicast routing protocol)
DWDM (dense wavelength division multiplexing)
DXC (digital cross-connect)

E1 etc
EAI (enterprise application integration)
EAMPS (extended advanced mobile phone system)
EAN (European Article Numbering Association). External web site.
EBGP (external border gateway protocol)
EBIT (earnings before interest and tax)
EBITDA (earnings before interest, tax, depreciation and amortisation)
EBU (European Broadcasting Union). External web site.
ebXML (e-business XML)
EC (European Commission)
ECA (Electronic Communications Act [UK])
ECAT (event collection and alarm translation)
ECBS (European Committee for Banking Standards). External web site.
ECCM (electronic counter counter measures)
ECL (emitter coupled logic)
ECM (electronic counter measures)
ECMA (European Computer Manufacturers Association - now ECMA International). External web site.
ECMF (equal cost multi-path forwarding)
ECMP (equal cost multi-path)
ECN (explicit congestion notification)
ECOM (Electronic Commerce Promotion Council of Japan). External web site.
ECSD (enhanced circuit switched data)
ECSS (European Cooperation for Space Standardisation). External web site.
ECTF (Enterprise Computer Telephony Forum). External web site.
EDD (earliest due date)
EDFA (erbium doped fibre amplifier)
EDGE (enhanced data-rate for GSM evolution)
EDI (electronic data interchange)
EDIFICE (The Standardised Electronic Commerce Forum for companies with interest in computing, and electronics and telecommunications)
EE (end entity)
EEMA (European Electronic Messaging Association). External web-site.
EEP (European Education Partnership). External web site.
EESSI (European electronic signature standardisation initiative)
EFR (enhanced full rate)
EGA (enhanced graphics adapter)
EGP (exterior gateway protocol)
EIA (Electronics Industries Alliance). External web site.
EICTA (European Information and Communications Technology Industry Association). External web site.
E-IDE (enhanced intelligent drive electronics)
EIDQ (Association for the European Interworking of Directory Inquiry services). External web site.
EIDX (Electronics Industry Data Exchange). External web site.
EISA (extended industry standard architecture)
EIR (equipment identity/information register)
EIRP (effective isotropic radiated power)
EIUF (European ISDN Users Forum)
ELF (extremely low frequency)
ELINT (electronic intelligence)
E & M (earth and mark signalling)
EMA (European Multimedia Forum)
EMC (electromagnetic compatibility)
EMEA (Europe, Middle East and Africa)
EMF (electromotive force [voltage])
EMI (electromagnetic interference)
EMP (electromagnetic pulse)
EMS (enhanced message service)
ENF (European Numbering Forum). External web site.
ENOB (effective number of bits)
ENUM (not an acronym - E164 number mapping)
E-OTD
EPD (early packet discard)
EPF (Electronics Payment Forum). External web site.
EPM (electronic protection measures)
EPOC (an operating system for small portable radio devices)
EPON (Ethernet passive optical network)
EPOS (electronic point of sale)
EPROM (erasable programmable read only memory)
EPS (earnings per share)
ER (explicit rate)
ERM (enterprise resource management)
ERP (enterprise resource planning)
ERP (effective radiated power)
E series specs (ITU, see standards)
E-SAN (Ethernet-based storage area network)
ES (end system)
ESD (electro-static discharge)
ESIGN (Electronic Signatures in Global and National Commerce Act - USA)
ESMTP (extended simple mail transfer protocol)
ESN (electronic serial number)
ESO (European standards organisations)
ESP (encapsulating security payload)
ESS (electronic switching system - USA)
ESS (extended service set)
ETIS (European Telecommunications Informatics Services). External web-site.
ETNO (European Telecommunication Network Operators). External web site.
ETP ( European Telecommunications Platform)
ETSI (European Telecommunications Standards Institute). External web-site.
ETX (end of text)
EU (European Union). External web site.
EVC (Ethernet virtual circuit)
EVRC (enhanced variable bit rate code)
EW (electronic warfare)
EWF (enterprise workflow)

FAB (fulfillment, assurance, billing)
FACCH (fast associated control channel)
FAMA (floor acquisition multiple access)
FBB (functional building block)
FC (fibre channel)
FCC (Federal Communications Commission - USA). External web-site.
FCCH (frequency correction channel)
FCIA (Fibre Channel Industry Association [Europe]). External web-site.
FCIP (fibre channel over Internet protocol)
FCS (frame check sequence)
FDD (floppy disk drive)
FDD (frequency division duplex)
FDDI (fibre distributed data interface)
fdm (frequency division multiplex)
FDMA (frequency division multiple access)
FE (fast Ethernet)
FE (functional entity)
FEA (functional entity action)
FEC (forward error correction)
FEC (forwarding equivalence class)
FEI (frame erasure indication)
FER (frame erasure rate)
FET (field effect transistor)
FEXT (far-end crosstalk)
FFE (feed forward equaliser)
FFT (fast Fourier transform)
FH (frequency hopping)
FHSS (frequency hopping spread spectrum)
FIFO (first in, first out)
FITL (fibre in the loop)
flops (floating-point operations per second)
FM (facilities management)
FM (frequency modulation)
FM3TR (future multiband multiwaveform modular tactical radio)
FMBS (frame mode bearer service)
FMD (follow-me diversion)
FMMC (Foundation for Multimedia Communications [Japan]). External web-site.
FN (frame number)
FOCC (forward control channel)
FoIP (fax over IP)
FPGA (field programmable gate array)
FR (frame relay)
FRF (Frame Relay Forum). External web-site.
FPLMTS (future public land mobile telecommunications system)
F-SAN (fibre channel storage area network)
FSAN (full service access network)
FSK (frequency shift keying)
FSM (finite state machine)
FSN (full service network)
FSO (free space optics)
FSR (fisheye state routing)
FSS (fixed satellite service)
FTA (full type approval)
FTC (Federal Trade Commission - USA). External web-site.
FTP (file transfer protocol)
FTTH (fibre to the home)
FTTK (fibre to the kerb)
FTTP (fibre to the premises)
FVC (forward voice channel)
FWA (fixed wireless access)

G-series (ITU recommendations for transmission systems)
GAAP (generally accepted accounting principles - USA)
GbE (gigabit Ethernet)
GBIC (gigabit interface converter)
Gbit/s[European], Gbps[USA] (gigabits per second)
GCK (group cipher key)
GCP (gateway control protocol)
GCRA (generic cell rate algorithm)
GDF (group distribution frame)
GE (gigabit Ethernet)
GEA (Gigabit Ethernet Alliance). Also known as 10GEA. External web-site.
GEK (group encryption key)
GEO (geostationary earth orbit)
GFC (generic flow control)
GFI (general format indicator)
GFP (generic frame protocol)
GFP (generic framing procedure [G704.1])
GFR (guaranteed frame rate)
GFSK (Gaussian frequency shift keying [DECT])
GGRF (The GSM Global Roaming Forum). External web-site.
GGSN (gateway GPRS support node)
GigE (gigabit Ethernet)
GII (global information infrastructure)
GIIF (Global ISDN Industry Forum). External web-site.
GLM (gigabit link module)
GLMS (group and list management server)
GMCF (Global Mobile Commerce Forum). External web-site.
GMLC (gateway mobile location centre)
GMPCS (global mobile personal communications system)
GMPLS (generalised multi-protocol label switching)
GMSC (gateway mobile switching centre)
GMSK (gaussian minimum shift key)
GoS (grade of service)
GPRS (general packet radio service)
GPS (global positioning satellite)
GRE (generic routing encapsulation)
GSA (Global Mobile Suppliers Forum). External web-site.
GSC (Global Standards Collaboration). External web site.
GSC (group switching centre - UK archaic)
GSM (global system for mobile [communication])
GSM-R (GSM railways)
GSN (gateway serving node)
GSO (geosynchronous orbit)
GTP (GPRS tunelling protocol)
GTS (general traffic shaping)
GTT (global title translation)
GUI (graphical user interface)
GUP (generic user profile)
GVF (Global VSAT [very small aperture terminal] Forum
GW (gateway)

H-series (ITU recommendations for audiovisual and multi-media systems)
HAN (home area network)
HAP/HAPS (high altitude platform - station)
HAVi (home audio visual interoperability)
HBA (host bus adapters)
HCI (human computer interaction)
HDB3 (high-density bipolar, 3 zeroes)
HDD (hard disk drive)
HDLC (high-level data link control)
HDMI (high definition multimedia interface)
HDTV (high definition television)
HE (home environment)
HEC (header error control/check)
HEMP (high-level entity management protocol)
HFC (hybrid fibre/co-ax)
HIPPI (high performance parallel interface)
HLA (high level architecture)
HLR (home location register)
HMI (human machine interface)
HMP (host monitoring protocol)
HNF (High-performance Networking Forum). external web-site.
HPF (high-pass filter)
HPNA (Home Phoneline Networking Alliance). External web-site.
HRFWG (Home-RF Working Group). Disbanded Jan 2003.
HSCSD (high speed circuit switched data)
HSDPA (high speed downlink packet access)
HSIA (high-speed Internet access)
HSN (hopping sequence number)
HSRP (hot standby router protocol)
HSS (home subscriber server)
HTML (hypertext markup language)
HTTP (hypertext transfer protocol)
HVAC (heating, ventilation and control)
HVD (high voltage differential)
HWC (hardware controller)

I-series (ITU recommendations for ISDN)
IA (interoperability agreements)
IAAC (Information Assurance Advisory Council). External web-site.
IAB (Internet Architecture Board). External web-site.
IAD ( integrated access device)
IAM (initial address message)
IANA (Internet Assigned Numbers Authority). External web-site.
IBGP (internal border gateway protocol)
IBIA (International Biometric Industry Association). External web-site.
IBSS (independent basic service set)
ICAP (Internet content adaptation protocol)
ICMP (Internet control message protocol) or (Internet control and management protocol)????
ICANN (Internet Corporation for Assigned Names and Numbers). External web-site.
ICI (interface control information)
ICMP (Internet control message protocol)
ICP (Internet cache protocol)
ICP (Internet content provider)
I-CSCF (interrogating call session control function)
ICT (information and communications technology)
ICTSB (ICT Standards Board - European standards coordinating body)
ICW (Internet call waiting)
ID (identity/identification)
IDC (Internet data centres)
IDCT (inverse discrete cosine transform)
IDD (international direct dialling)
IDE (intelligent drive electronics)
IDF (intermediate distribution frame)
IDFT (inverse discrete Fourier transform)
IDPKC (indentifier-based public key cryptosystem)
IDPR (inter-domain policy routing protocol)
IDRP (inter-domain routing protocol)
IDS (intrusion detection system)
IDU (interface data unit)
IE (information element)
IEC (International Electrotechnical Commission). External web-site.
IEE Institution of Electrical Engineers - UK). External web-site.
IEEE (Institute of Electrical and Electronic Engineers - USA). External web-site.
IEI (information element identifier)
IEPS (international emergency preference scheme)
IESG (Internet Engineering Steering Group). External web-site.
IETF (Internet Engineering Task Force). External web-site.
IF (intermediate frequency)
IFCP (Internet fibre channel protocol)
IFF (identification friend or foe)
IFIP (International Federation for Information Processing). External web-site.
IGMP (Internet group management protocol)
IGP (interior gateway protocol)
IGP (Internet gateway protocols)
IGRP (interior gateway routing protocol)
IHL (in-field header length)
IIA (Internet Industry Association [Australia]. external web-site.
IK (integrity key)
IKBS (intelligent knowledge-based system)
IKE (Internet key exchange)
ILEC (incumbent local exchange carrier)
ILS (Internet locator service)
IM (instant messaging)
IM (intermodulation)
IM (Internet Protocol multi-media)
IMAP (interactive mail access protocol)
IMC (Internet Mail Consortium). External web-site.
IMD (inter-modulation distortion)
IMEI (international mobile equipment identifier)
IMP (interface message processors)
IMPP (instant messaging and presence protocol)
IMS (intelligent media server)
IMS (Internet Protocol multi-media sub-system)
IMSI (international mobile subscriber identity)
IMT (international mobile telecommunications)
IMT 2000 (international mobile telecommunications 2000. Global standard for 3G - ITU)
IMTC (International Multimedia Teleconferencing Consortium). External web-site.
IMTS (improved mobile telephone system)
IN (intelligent network)
INAP (intelligent network application part/protocol)
InARP (inverse address resolution protocol)
INC (Industry Numbering Committee). External web-site.
INCITS (National Committee for Information Technology Standards). External web-site.
INCM (intelligent network conceptual model)
INL (integral non-linearity)
INTUG (International User Group). External web-site.
ILEC (incumbent local exchange carrier)
I/O (input/output)
IOC (Internet operations centre)
IP (intellectual property)
IP (intelligent peripheral)
IP (Internet protocol)
IPC (international private circuit)
IP-CAN (Internet Protocol connectiviy access network)
IPCF (International Powerline Communications Forum). External web-site.
IPDC (Internet protocol device control)
IPDR (IP detail record)
IPI (intelligent peripheral interface)
IPLC (international private leased circuit)
IPMI (IP Multicast Initiative)
IPMP (intellectual property management and protection [MPEG])
IPNS (ISDN PBX Network Specification [Forum]). External web-site.
IPO (initial public offering - of shares)
IPP (Internet printing protocol)
IP-PBX (IP-based private branch exchange)
IPR (intellectual property rights)
IPRA (Internet policy registration authority)
IPsec (IP security protocol)
IPTN (international public telecommunications number)
IPv4 (Internet protocol version 4)
IPv6 (Internet protocol version 6)
IPVPN (Internet protocol virtual private network)
IPX (connectionless internetworking protocol)
IPX (internetwork packet exchange)
IR (infra-red)
IRC (Internet relay chat)
IrDA (Infrared Data Association). External web-site.
IRQ (interrupt request)
IRR (information request response)
IRTF (Internet Research Task Force). External web-site.
IRTP (Internet reliable transaction protocol)
IS, e.g. IS95, IS136 (interim standard - USA)
IS (intermediate system)
ISA (integrated services access)
ISA (industry standard architecture) PC bus
ISAKMP (Internet security association and key management protocol)
ISC (intelligent system controller)
ISC (International SoftSwitch Consortium) - or Internet...?????
ISC (international switching centre)
ISC (Internet Software Consortium). External web-site.
iSCSI (i SCSI ??)
ISDN (integrated services digital network)
ISI (intersymbol interference)
ISIM (Internet Protocol multi-media services identity module)
ISM (instrumentation, scientific and medical - frequency band)
ISMA (Internet Streaming Media Alliance). External web-site.
ISMS (information security management system)
ISO (International Standards Organisation). External web-site.
ISOC (Internet Society). External web-site.
ISP (intermediate services part)
ISP (Internet service provider)
ISPBX (integrated services PBX)
ISS (interference suppression subsystem)
ISSP (inter-softswitch signalling protocol)
ISSS (Information Society Standardisation System - department of CEN)
ISTP (Internet signalling transport protocol)
ISUP (integrated services user part) - SS7
ISV (independent software vendor)
IT (information technology)
ITG (Internet telephony gateway)
ITS (intelligent transportation system)
ITSI (individual terminal subscriber identity)
ITSP (Internet service provider)
ITT (invitation to tender)
ITU (International Telecommunications Union). External web-site.
ITU-T (International Telecommunications Union - telecommunications standardisation sector). External web site.
ITU-R (International Telecommunications Union - radio standardisation sector)
IUA (Q921 user adaptation layer)
IUC (interval usage codes)
IVR (interactive voice response)
IWA (International Webcasting Association). External web-site.
IWF (interworking function)
IWU (interworking unit)
IXC (inter-exchange carrier)

J2EE (Java 2 enterprise edition)
J2ME (Java 2 micro-edition)
J2SE Java 2 standard edition)
JAIN (Java API for integrated network)
JCF (Java Card Forum). External web-site.
JDC (Japanese digital cellular)
JDK (Java developers kit)
JIMM (Joint Initiative toward Mobile Multimedia)
JIT (just in time)
JTACS (Japanese total access communications system)
JPEG (joint photographic experts group)
JV (joint venture)
JVM (Java virtual machine)

kbit/s (kilobits per second) kbps in USA
KDC (key distribution centre)
KEK (key encryption key)
KISS (keep it simple, stupid - designers watchword)
KM (knowledge management)

L1, 2, etc (layer 1, 2 etc)
L2F (layer 2 forwarding)
L2ML (layer 2 management link)
L2TP (layer 2 tunnelling protocol)
LAC (L2TP access concentrator)
LAC (location area code)
LACNIC (Latin American and Caribbean Internet Addresses Registry)
LAI (location area identity)
LAN (local area network)
LAP (link access procedure)
LAPB (link access procedure, balanced)
LAPD (link access procedure for digital) - or for D-channel????###########
LAPF (link access procedure for frame relay)
LAPM (link access procedure for modems)
LASER (light amplification by stimulated emission of radiation)
LATA (local access and transport area - USA)
LATNIC (Latin American network information centre)
LCAS (link capacity adjustment scheme [G704.2])
LCD (liquid crystal display)
LCF (location confirm)
LCGN (logical channel group number)
LCN (local channel number)
LCP (link control protocol)
LCP (local control point)
LCR (least cost routing)
LD (loop disconnect)
LDAP (lightweight directory access protocol)
LDP (label distribution protocol)
LDP (loader debugger protocol)
LE (local exchange)
LE (listening effort)
LEAP (lightweight efficient application protocol)
LEC (local exchange carrier)
LED (light emitting diode)
LEO (low earth orbit)
LEO (Lyons electronic office - early UK computer)
LES (land earth station)
LF (low frequency)
LFAP (lightweight flow admission protocol)
LFS (location fixing system)
LI (length indicator)
LIF (Location Interoperability Forum). See external web-site.
LIFO (last in first out)
LLC (logical link control)
LLPE (low latency processing element)
LLU (local loop unbundling)
LMCS (local multi-point communication system)
LMDS (local multi-point distribution system)
LMS (least mean squares)
LMT (local maintenance terminal)
LMTP (local-mail transfer protocol)
LNA (low noise amplifier)
LNB (low noise block - low noise amplifier and block downconverter - for satellite dish)
LNP (local number portability)
LNS (L2TP network server)
LO (local oscillator)
LOB (line of business)
LOS (line of sight)
LPC (linear predictive coding)
LPD (link protocol discriminator)
LPF (low-pass filter)
LQ (listening quality)
LRC (longitudinal redundancy checking)
LRJ (location reject)
LRQ (location request)
LRU (line replaceable unit)
LS (LAN emulation server)
LSA (link state advertisement) - multicasting
LSAP (link service access points)
LSB (lower sideband)
LSI (large-scale integration)
LSP (label switched path)
LSR (label switched router)
LTCS (long-term capability set)
LTE (line terminating equipment)
LTP (long-term prediction - in speech coding)
LU (line unit)
LUT (look up table)
LVD (low voltage differential)
LWA (leaky-wave antennas)

M2M (machine to machine)
M2PA (message transfer part 2 user peer-to-peer adaptation layer)
M2UA (message transfer part 2 user adaptation layer)
M3A (mobile multi media access)
M3UA (message transfer part 3 user adaptation layer)
M&A (mergers and acquisitions)
MAC (media/medium access control)
MAC (message authentication code)
MACA (multiple access with collision avoidance)
MACAW (multiple access with collision avoidance wireless)
MACF (multiple association control function)
MAE (metropolitan area exchange)
MAIO (mobile allocation index offset)
MAN (metropolitan area network)
MANET (mobile ad-hoc network)
MAP (mobile application part)
MAP (membership approval procedure - ETSI)
MAU (medium attachment unit)
MBAC (measurement based admission control)
MBB (make before break)
Mbone (multicast backbone)
MBS (maximum burst size)
MC (media control [layer])
MCC (mobile country code)
MCCS (mobile call control signalling)
MCI (malicious caller identification)
MCR (minimum cell rate)
MCS (master control station)
MCU (media control unit)
MCU (multi-point control unit)
MDA (Mobile Data Association). External web-site.
MDCP (media device control protocol)
MDF (main distribution frame)
MDI (medium dependent interface)
MDI-ng (mobile data initiative - next generation).
MDU (multi dwelling unit)
MED (multi-exit discriminator)
MEF (Metro Ethernet Forum). External web-site.
Megaco (media gateway control)
MEGACOP (media gateway control protocol)
MEM (mediation element manager)
MEMS (micro electromechanical system)
MEO (medium earth orbit)
MeT (Mobile Electronic Transactions Alliance). External web-site.
MExE (mobile execution environment)
MF (medium frequency)
MF (multi-frequency)
MFPA (Multifunction Products Association). External web-site.
MG (media gateway)
MGC (media gateway controller)
MGCF (mobile/media gateway control function)
MGCP (mobile gateway control protocol)
MGF (media gateway function)
MGW (media gateway)
MHP (multimedia home platform)
MIB (management information base)
MID (multiplexing identification)
MIDCOM (middlebox communications protocol [IETF])
MIDI (musical instrument digital interface)
MIMD (multiple instruction, multiple data)
MIME (multi-purpose Internet mail extension)
MIMO (multiple input/multiple output)
MIN (mobile identity number)
MIPS (millions of instructions per second)
MJPEG/M-JPEG (moving JPEG - joint photographic experts group)
MLD (multicast listener discovery)
MLPPP (multi-link point-to-point protocol)
MLSE (maximum likelihood sequence estimation)
MM (mobility management)
MMAC (Multimedia Mobile Access Communications Systems Promotion Council [Japan]). External web-site.
MMCF (Multimedia Communications Forum). External web-site.
MMDS (multi-channel multi-point distribution service)
MMF (Mobile Manufacturers Forum). External web-site.
MMF (multi mode fibre)
MMI (man machine interface - see also HMI)
MMS (mobility management signalling)
MMS (multi-media messaging service)
MMSE (minimum mean square error)
MMSF (media mapping and switching function)
MMTA (Multimedia Telecommunications Association. Now part of Telecommunications Industry Association [USA])
MNC (mobile network code)
MOC (mobile originated call)
MoIP (multi-media over IP)
MOP (mean opinion score)
MOSPF (multicast open shortest path first)
MoU (memorandum of understanding)
MP3 (contraction of: MPEG1 layer 3 audio)
MPE (multi-protocol encapsulation)
MPEG (moving pictures expert group)
MPLS (multi protocol label switching)
MPR (multipoint relays)
MPRN (multi-protocol router network)
MR2RP (multi-rate and multi-range routing protocol)
MRC (monthly rental charge)
MS (mobile station)
MSA (metropolitan statistical area)
MSAN (multi-service access node)
MSC (main switching centre)
MSC (mobile switching centre)
MSC (multimedia super corridor - Malaysia)
MSDU (MAC service data units)
MSE (mean square error)
MSE (MeXE service environment)
MSF (Multiservice Switching Forum). External web-site.
MSIC (mobile subscriber identification number)
MSIGN (Mobile Electronic Signature Consortium). External web-site.
MSK (minimum shift keying)
MSN (multiple subscriber number)
MSO (multiple system operator - cable TV)
MSP (managed service provider)
MSRN (mobile subscriber routing number)
MSS (mobile satellite service)
MT (message type)
MTA (multimedia terminal adapter)
MTBF (mean time between failures)
MTC (mobile terminated call)
MTP (mail transfer protocol)
MTP (message transfer part) - SS7
MTP (multicast transfer protocol)
MTS (mobile telephone service)
MTSO (mobile telephone switching office)
MTTR (mean time to repair)
MTU (maximum transmission/transfer unit)
MTU (multi-tenanted unit)
MUF (maximum usable frequency)
MV (mandatory variable [length])
MVDR (minimum-variance distortionless response)
MVNO (mobile virtual mobile operator)
MWIF (Mobile Wireless Internet Forum). External web-site.
MX (mail exchange)
MZAP (multicast-scope zone announcement protocol)

NA (numerical aperture)
NADC (North American digital cellular)
NADH (North American digital hierarchy)
NAI (network address identifier)
NAMPS (narrowband advanced mobile phone system)
NANOG (North American Network Operators Group). External web-site.
NANP (North American numbering plan)
NAP (network access point)
NAPT (network address and port translation)
NAPT-PT (network address - port multiplexing - translation - protocol translation)
NAPTR (naming authority pointer)
NAS (network access server)
NAS (network attached storage)
NAT (network address translation)
NAV (net asset value)
NAV (network allocation vector)
NBMA (non-broadcast multiple access)
NCDMA (narrowband code division multiple access
NCP (network control point)
NCP (network control protocol)
NCP (network core protocol)
NCR (network clock reference)
NCSA (National Center for Supercomputing Applications). External web-site.
NDC (national destination code)
NDMP (network data management protocol)
NEBS (network equipment building standards - USA)
NEC (network enabled communications - military)
NEP (noise equivalent power)
NEXT (near-end crosstalk)
NG (next generation)
NGI (next generation Internet)
NGN (next generation network[s])
NGS (next generation switch)
NFC (near-field communication)
NFM (network fault manager)
NFS (network file system)
NHLFE (next-hop label-forwarding entries)
NHRP (next hop routing protocol)
NIC (network interface card)
NiCd (nickel cadmium)
NIF (nodal interworking function)
NIH (not invented here!)
NIIF (National Interconnection Interoperability Forum). External web-site.
Ni-MH (nickel metal hydride)
N-ISDN (narrowband integrated services digital network)
NISM (network inventory and spares management)
NISO (National Information Standards Organisation). External web-site.
NIST (National Institute of Standards and Technology - USA). External web-site.
NIUF (North American ISDN Users Forum). External web-site.
NM (network management)
NMC (network management centre)
NMDA (New Media Development Association) - Japan. External web-site.
NMF (Network Management Forum). www.nmf.org - check###############
NMP (Nordic mobile telephone [system])
NMS (network management system)
NMT (Nordic mobile telephone system)
NNI (network-to-network number) #########
NNTP (network news transfer protocol)
NOC (network operations centre)
NPA (numbering plan area - USA)
NPF (Network Processing Forum). External web-site.
NREN (national research and educational network - USA)
NRTVBR (non real time variable bit rate)
NRZ (non-return to zero)
NRZI (non-return to zero, inverse)
NS (name server)
NSA (National Security Agency - USA). External web-site
NSF (National Science Foundation). External web-site.
NSIF (Network and Services Integration Forum). External web-site.
NSN (national significant number)
NSAP (network-layer service access point)
NSO (national standards organisation)
NSP (network services part)
NSS (network sub-system)
NT (network termination)
NTACS (narrowband total access communications system)
NTE (network terminating equipment)
NTSC (National Television Standards Committee - USA)
NUA (network user address)
NUP (network user part)
NVIS (near-vertical incidence sky-wave)

OADM (optical add-drop multiplexer)
OAG (Open Applications Group). External web-site.
OAM/O&M (operations, administration and maintenance/operations and maintenance)
OASIS (Organisation for the Advancement of Structured Information Standards - for XML). External web-site.
OBF (Ordering and Billing Forum)
OBI (open buying on the Internet)
OC (optical carrier, OC1 = level 1, etc)
OCPM (optical channel performance monitors)
OCSP (on-line certificate status protocol)
ODBC (open database connectivity)
ODMG (Open Object Management Group). External web-site.
ODMRP (on-demand multi-cast routing protocol)
ODP (open distributed processing)
ODRL (open digital rights language)
ODU (optical data unit)
OED (optical edge device)
OEM (original equipment manufacturer)
OEO (optical-electrical-optical)
OFDM (orthogonal frequency division multiplexing)
O/H (overhead)
OHG (Open Harmonisation Group) or O for Operator?????
OIF (Optical Internetworking Forum). External web-site.
OLC (open logical channel)
OLE (object linking and embedding)
OLO (other licenced operator)
OLSR (optimised link state routing - protocol for ad-hoc networks)
OLT (optical line termination)
OLTP (on-line transaction processing)
OMA (Open Mobile Alliance). External web-site.
OMC (operations and maintenance centre)
OMG (Object Management Group). External web-site.
ONU (optical network unit)
OO (object oriented)
OOB (out of band)
OOO (optical, optical, optical)
OOP (object oriented programming)
OPC (originating point code)
OPIMA (Open Platform Initiative for Multimedia Access). External web-site.
OPQSK (offset quadrature phase-shift keying)
ORB object request broker)
ORPK (operator root public key)
OS (operating system)
OSA (open services architecture)
OSA (open systems access)
OSF (open software foundation)
OSGi (open services gateway initiative)
OSI (open systems interconnection)
OSIRM (open systems interconnection reference model)
OSNR (optical signal to noise ratio)
OSP (open settlement protocol)
OSPF (open shortest path first)
OSS (open source software)
OSS (operational support systems)
OSS/J (Operational Support Systems through Java)
OS X (Unix based operating system used by Apple)
OTA (over the air)
OTAR (over the air re-keying)
OTDA (observed time difference of arrival)
OTDM (optical time division multiplexing)
OTDR (optical time domain reflection/reflectometer)
OTN (optical transport network)
OVSF (orthogonal variable spreading factor)
OXC (optical cross-connect)

P2P (peer to peer)
P2P (person to person)
P2T (push to talk)
P&L (profit and loss)
PABX (private automatic branch exchange)
PACS (personal access communication system)
PACS (planning, assignment and configuration system)
PAD (packet assembler/dis-assembler)
PAL (phase alternating line)
PAM (pulse amplitude modulation)
PAMR (public access mobile radio)
PAMS (perceptual analysis measurement system)
PAN (personal area network)
PAR (positive acknowledgement with retransmission)
PAS (publicly available specification [ETSI])
PAT (port address translation)
PBN (policy based networks)
PBX (private branch exchange)
PC (personal computer)
PCA (percentage calls answered)
PCA (polar cap absorption)
PCA (policy certification authorities)
PCCA (Portable Computer and Communications Association). External web-site.
PCF (packet control function)
PCI (peripheral component interconnect)
PCI-X (higher performance version of PCI)
PCK (primary correlation key)
PCM (pulse code modulation - but also see PCMCIA)
PCMCIA (personal computer memory card international association - sometimes "PCM card")
PCN (personal communications network)
PCR (peak cell rate)
PCS (personal communications system)
PCS (physical coding sublayer)
P-CSCF (proxy call session control function)
PCU (packet control unit)
PD (potential difference)
PD (protocol discriminator)
PDA (personal digital assistant)
PDC (personal digital cellular - standard: Japan)
PDCP (packet data convergence protocol)
PDD (post-dial delay)
PDF (policy decision function)
PDH (plesiochronous digital hierarchy)
PDL (policy description language)
PDN (packet data network)
PDN (public data network)
PDP (packet data protocol)
PDR (programmable digital radio)
PDSN (packet data serving node)
PDU (protocol data unit)
PE (provider edge [router])
PEF (policy enforcement function)
PEM (privacy enhanced mail)
PER (packet encoding rule)
PER (power equipment rack)
PES (packetised elementary stream)
PESQ (perceptual evaluation of speech quality)
PEW (planned engineering works)
PGP (pretty good privacy)
PHB (per hop behaviour)
PHP (penultimate hop popping)
PHP (PHP: hypertext preprocessor - a recursive acronym). External web-site.
PHS (personal handyphone system)
PHY - not an acronym: a contraction of physical [layer in the OSI model]
PIC (point in call)
PICS (protocol implementation conformance specification)
PID (packet identifier)
PIG (PSTN-to-IP gateway)
PIM (protocol independent multicast)
PIN (P-type intrinsic N-type) - type of photo diode
PIN (personal identification number)
PINT (PSTN and Internet interworking [IETF])
PIR (peak information rate)
PIUR (platform independent usage record)
PIWF (protocol interworking function)
PKC (public key cryptography)
PKI (public key infrastructure)
PKIXCMP (X509 PKI certificate management protocol)
PLL (phase locked loop)
PLMN (public land mobile network)
PLS (physical layer signalling)
PM (phase modulation)
PMA (physical medium attachment)
PMD (physical medium dependent)
PMD (polarisation mode dispersion)
PMI (21CN presn - ???)
PMLCD (passive matrix liquid crystal display)
PMMB (provided, maintained, monitored and billed)
PMR (private mobile radio)
PMRTS (public mobile radio trunked system)
PN (personal number[ing])
PNNI (private network node interface)
PNNI (private network-to-network interface)
PNO (public network operator)
PnP (plug 'n play)
POF (plastic optical fibre)
PON (passive optical network)
PoP (point of presence)
POS (packet over SONET)
POSIX (portable operating system interface)
POT (pyramid of trust)
POTS (plain old telephony service)
PPD (partial packet discard)
PPM (pulse position modulation)
PPP (point-to-point protocol)
PPPoE (point-to-point protocol over Ethernet)
PPTP (point-to-point tunneling protocol)
PPVPN (provider provisioned virtual private network)
psk (phase shift keying)
PSDN (public switched data network)
PRA (primary rate access)
PRBS (pseudo-random bit sequence)
PRI (primary rate interface)
PRI (primary rate ISDN)
PRN (packet radio network)
PR-QMF (perfect reconstruction quadrature mirror filter)
PS (packet switched/switching)
PSCF (pure silica core fibre)
PSD (power spectral density)
PSI (public service identity)
PSK (phase-shift keying)
PSQM (perceptual speech quality measure)
PSTN (public switched telephone network)
PSU (power supply unit)
PTF (Power Line Telecommunications Forum). External web-site.
PTI (packet type identifier)
PTI (payload type)
PTO (public telecommunications operator)
PTP (performance transparency protocol)
PTR (not an acronym - contraction of pointer)
PTT (Post Telephones and Telegraph)
PTT (push/press to talk)
PUA (personal user agent)
PUC (Public Utility Commission - USA).
PUK (personal unblocking key)
PVC (permanent virtual connection/circuit/channel)
PVR (personal video recorder)
PWE3 (pseudo wire emulation edge-to-edge)
PWM (pulse width modulation)

QAM (quadrature amplitude modulation)
QC (quantum cascade - laser)
QDDFS (quadrature direct digital frequency synthesis)
QFME (Q-factor measuring equipment)
QoS (quality of service)
QPSK (quadrature phase shift keying)
QSIG (signalling at the Q reference point [ECMA standard])
QTP (quick transaction protocol)

RA (Radiocommunications Agency - UK). External web-site.
RA (registration authority)
RA (rural area)
RAB (radio access barrier)
RACH (random access channel)
RACS (resource and admission control subsystem)
RADIUS (remote authentication dial-in user service)
RAG (red, amber, green - of activity reporting status)
RAID (redundant array of independent drives)
RAKE (radio activated key entry)
RAM (random access memory)
RANAP (radio access network application protocol)
R&D (research and development)
RAP (radio access point)
RAP ([Internet] route access protocol)
RARP (reverse address resolution protocol)
RAS (registration, admission and status)
RAS (remote access service)
RAT (radio access technologies)
RBER (residual bit error ratio)
RBOC (Regional Bell Operating Company)
RCC (radio common carrier)
RCCS (radio channel control signalling)
RCF (registration confirm)
RCP (reconfigurable communications processor)
RCR (Research and Development Centre for Radio Systems) - now part of ARIB
RCS (return channel satellite)
RDBMS (relational database management system)
RDD (rights data dictionary [MPEG])
RDL (radio description language)
RDP (reliable data protocol)
RDRAM
RECC (reverse control channel)
RED (random early detection)
REL (rights expression language [MPEG])
RF (radio frequency)
RFC (request for comment)
RFI (request for information)
RFI (radio frequency interference)
RFID (radio frequency identification)
RFP (request for proposal)
RFQ (request for quotation)
RG (residential gateway)
RGB (red, green, blue)
RGMP (router-port group management protocol)
RIB (routing information base)
RIL (radio interface layer)
RIP (routing information protocol)
RIPE (Reseaux Internet Protocol Europeens). External web-site.
RIR (regional Internet registries)
RISC (reduced instruction set computers)
RJ - RJ11/RJ45 etc (registered jacks - USA)
RLC (radio link control)
RLEC (rural local exchange carrier)
RLP (resource location protocol)
RM (resource management)
RMCP (remote mail chacking protocol)
RMI (remote method invocation)
RMS (root mean square)
RN (radio network)
RNC (radio network controller)
ROCE (return on capital employed)
ROI (return on investment)
ROM (read only memory)
ROPA (remote optically pumped optical amplifier)
ROSE (remote operations service)
RPE (regular pulse excitation)
RPC (remote procedure call)
RPK (root public key)
RPR (resilient packet ring)
RR (radio resource)
RRC (radio resource control)
RRJ (registration reject)
RRQ (registration request)
RS (reconciliation sublayer)
RSA (public key protocol named after inventors: Rivet/Shamir/Adleman)
RSA (rural service area)
RSL (radio signalling link)
RSS (received signal strength)
RSSI (received signal strength indication)
RSSU (remote subscriber switching unit)
RSVP (resource reservation protocol)
RSVP-TE (resource reservation protocol - traffic engineered)
RTCP (real time control protocol)
RTL (resistor transistor logic)
RTO (regional telephone operator)
RTO (retransmit timeout)
RTOS (real time operating system)
RTSP (real time streaming protocol)
RTP (real time protocol)
RTR (reliable transaction router)
RTT (round trip time)
RTTP (real-time transport protocol)
RTTT (road transport and traffic telematics)
RTVBR (real-time variable bit rate)
RVC (rural area)
Rx/RX (receiver)

S2ML (security services mark-up language)
SAAL (signalling ATM adaptation layer)
SAB (start at beginning)
SABM (set asynchronous balanced mode)
SAC (service access code - USA)
SACCH (slow associated control channel)
SACD (super audio compact disc)
SACF (single association control function)
SA/DA (source address/destination address)
SAML (security assertion mark-up language)
SAN (storage area network)
SAO (single association object)
SAP (service access point)
SAP (service advertising protocol)
SAP (session announcement protocol)
SAP (speech applications platform)
SAPI (service-access point identifier)
SAR (segmentation and re-assembly)
SAT (source address table)
SAT (supervisory audio tones)
SAW (surface acoustic wave)
SAX (simple API for XML)
SB (systems business - UK)
SBC (sub band coding)
SBR (software based radio)
SC (service control [layer])
SC (signalling controller)
SCADA(supervisory control and data acquisition)
SCAI (switch-computer applications interface - the ANSI standard for CTI)
SCCP (signalling connection control part) - SS7
SCCS (selective class of call screening)
SCE (service creation environment)
SCEF (service creation environment function)
SCTP (stream control transmission protocol)
SCF (service control function)
SCH (synchronisation channel)
SCK (static cipher key)
SCM (station class mark)
SCM (supply chain management)
SCP (service control point) - IN
SCR (sustained cell rate)
SCRF (session control and routing function)
SCU (service/system control unit)
SCS (service capability server)
SCSA (Signal Computing System Architecture [Initiative] CHECK THIS
S-CSCF (serving call session control function)
SCSI (small computer systems interface)
SCTP (stream control transmission protocol)
SCVP (simple certificate validation protocol)
SDCCH (standalone dedicated control channel)
SDF (service data function)
SDF (supergroup distribution frame)
SDP (session description protocol)
SDH (synchronous digital hierarchy)
SDL (specification and description language)
SDLC (synchronous data link control)
SDM (space division multiplexing)
SDMA (space division multiple access)
SDMI (Secure Digital Music Initiative). External web-site.
SDO (standards development organisations)
SDP (service data point)
SDP (session description protocol)
SDR (software defined radio)
SDRAM (synchronised dynamic random access memory)
SDRF Software Defined Radio Forum). External web-site.
SDS (short data service)
SDSL (symmetric digital subscriber line)
SDU (service data unit)
SEAL (simple efficient adaptation layer)
SECAM (sequential colour with memory/sequential couleur avec memoire)
SECBR (severely errored cell block ratio)
SEP (signalling end-point)
SFD (start frame delimiter)
SFH (slow frequency hopping)
SFI (special faults investigation)
SG (signalling gateway)
SG (study group [ITU-T])
SGCP (signalling gateway control protocol)
SGML (standard generalised mark-up language)
SGMP (simple gateway monitoring protocol)
SGSN (serving GPRS support node)
SGW (signalling gateway)
SHA (secure hash algorithm)
SHDSL (symmetric high bit-rate digital line system)
SHF (super high frequency)
SHR (self-healing rings)
SI (systems Integration)
SIB/SIBB (service-independent building block)
SIC (sequential interference cancellation)
SID (silence descriptor)
SID (sudden ionospheric disturbances)
SID (system identification number)
SIF (SONET [synchronous optical network] Interoperabilty Forum). Now NSIF - external web-site.
SIG (special interest group)
SIM (subscriber identity module)
SIMD (single instruction, multiple data)
SIMM (single in-line memory module)
SIMO (single input/multiple output)
SIN (supplier information note - UK)
SINAD (signal plus noise and distortion)
SINR (signal to interference-plus-noise ratio)
SIP (session initiation protocol)
SIPP (simple internet protocol plus)
SIR (signal to interference ratio)
SKEME (secure key exchange mechanism)
SLA (service level agreement)
SLD (semiconductor laser diode)
SLEE (service logic execution environment)
SLF (subscription locator function)
SLFCS (survivable low frequency communications system)
SLG (service level guarantee)
SLI (service logic interpreter)
SLIP (serial line internet protocol)
SLPR (shared lambda protection ring)
SLS (signalling link selection)
SLTU (subscribers line terminating unit)
SLP (service location protocol)
SLP (service logic program)
SMAF (service management agent function)
SMDS (switched multi-megabit data service)
SME (service management environment)
SME (small/medium enterprise)
SMF (service management function)
SMF (single mode fibre)
SMG (Special Mobile Group - ETSI) - absorbed into 3GPP.
SMI (structure of management information)
S/MIME (secure multi-purpose Internet mail extension)
SMS (short message service)
SMS (service management system)
SMT (surface mount technology)
SMTP (simple mail transfer protocol)
SMU (service management unit)
SN (service node)
S/N (signal to noise ratio)
SNA (system network architecture - International Business Machines trademarked)
SNCP (subnetwork connection protection)
SNIA (Storage Networking Industry Association). External web-site.
SNMP (simple network management protocol)
SNR (signal to noise ratio)
SOA (start of authority)
SOAP (simple object access protocol)
SoC (system on a chip)
SOHO (small office, home office)
SONET (synchronous optical network)
SP (service provider)
SPAN (services and protocols for advanced networks [ETSI]). External web-site.
SPC (stored program control)
SPD (serving profile database)
SPD (security policy database)
SPE (synchronous payload envelope)
SPF (shortest path first)
SPKI (secure public key infrastructure)
SPM (self-phase modulation)
SPM (subscriber private metering)
SPN (service protection network)
SPOF (single point of failure)
SPRing (shared protection ring)
SQL (structured query language)
SQN (sequence number)
SR (software radio)
SRF (service resource function)
SRF (specialised resource function)
SRNS (serving radio network subsystem)
SS (signalling system)
SS (supplementary services)
SS7 (signalling system number 7)
SSB (single sideband)
SSB (supplementary services business - UK)
SSCF (service specific co-ordination function)
SSCOP (service-specific connection-oriented protocol)
SSCOPMCE (service-specific connection-oriented protocol in a multi-link and connectionless environment)
SSF (service switching function)
SSG (special study group [ITU-T])
SSID (service set identifier - e.g. for WLAN)
SSL (secure sockets layer)
SSO (single sign-on)
SSP (service switching point) - IN
SSP (storage service provider)
ST (segment type)
STA (spanning tree algorithm)
STB (set top box)
STC (signalling transport converter)
STD (subscriber trunk dialling
STF (specialist task force [ETSI])
STK (subscriber identification module toolkit)
STLP (secure transport layer protocol)
STM (synchronous transfer mode)
STMn (synchronous transport module, level n)
STP (screened/shielded twisted pair)
STP (signalling transfer point) - IN
STS (space time space)
STS (synchronous transport signal- STS1, STS2 etc, SONET)
STX (start of text)
SVC (switched virtual connection)
SVG (scaleable vector graphics)
SVGA (super video graphics array)
SW (switch)
SWR (standing wave ratio)
SXGA (super extended graphics array)

T1 etc (trunk, level 1 - USA transmission standard)
T1 (a standards committee of Alliance for Telecommunications Industry Solutions)
TA (terminal adapter)
TAA (TETRA encryption algorithm)
TACS (total access communications system)
TAPI (telephony applications programming interface - Microsoft)
TAR (temporary alternative routing)
TASC (telecommunications applications for switches and computers - the ITU standard for CTI)
TASI (time assignment speech interpolation)
TBE (toll billing exception)
TBRPF (topology broadcast based on reverse path forwarding - protocol for ad-hoc networks)
TBTP (terminal burst time plan)
TC (transaction capability)
TC (transform coding)
TC (transmission convergent)
TCAP (transaction capabilities application part) - SS7
TCH (traffic channel - sometimes with FS [full rate speech] or HS [half-rate speech])
TCIF (Telecommunications Industry Forum). External web-site.
TCO (total cost of ownership)
TCP (transmission control protocol)
TCPH (transmission control protocol header)
TCP/IP (transmission control protocol/Internet protocol)
TCS (terminal capability set)
TDD (time division duplex)
TDM (time division multiplex)
TDMA (time division multiple access)
TDoA (time difference of arrival)
TDP (tag distribution protocol)
TD-SCDMA (time division synchronous code division multiple access)
TE (traffic engineering)
TEA (TETRA encryption algorithm)
TEI (terminal endpoint identifier) or e for equipment?????
TEI (TETRA equipment identity)
telco (telecommunications company)
TETRA (terrestrial trunked radio)
TFO (tandem free operation)
TFT (thin film transistor)
TFTP (trivial file transfer protocol)
TGS (ticket granting server)
THD (total harmonic distortion)
THIG (topology hiding inter-network gateway)
TI (transaction identifier)
TIA (Telecommunications Industry Association). External web-site.
TIES (Telecommunications Information Exchange - ITU documents on-line). Web-site for subscribers only.
TINA (telecommunications information network architecture)
TINA-C (telecommunications information network architecture consortium)
TIP (terminal interface processor)
TIPHON (telecommunications Internet protocol harmonisation over networks [ETSI]). External web-site.
TKIP (temporal key integrity protocol)
TLC (transmit level control)
TLS (transport layer security)
TMF ( TeleManagement Forum). External web-site.
TMN (telecommunications management network)
TMSI (temporary mobile subscriber identity)
TMT (technology, media and telecommunications)
TOA/ToA (time of arrival)
TOG (The Open Group). External web-site.
TOI (third order intercept)
TORA (temporally ordered routing algorithm)
ToS (taken out of service)
ToS (type of service)
TPC (Transaction Processing Performance Council). External web-site.
TPC (transmit power control)
TPDU (transport protocol data unit)
TRAU (transcoder rate adapter unit)
TrGW (translation gateway)
TRIP (telephony routing over IP)
TS (technical specification [IETF])
TS (time slot)
TS (transport stream)
TSAG (Telecommunication Standardisation Advisory Group). External web-site.
TSAP (transport-layer service access point)
TSAPI (telephony services applications programming interface (Novell)
TSB (Telecommunication Standardisation Bureau). External web-site.
TSC (transit switching centre)
TSG (technical sub-group)
TSI (time slot interchange)
TSN (transit serving node)
TST (time space time)
TTA (Telecommunications Technology Association - Korea). External web-site.
TTC (Telecommunication Technical Commission - Japan). External web-site.
TTCN (tree and tabular combined notation)
TTL (time to live)
TTL (transistor-transistor logic)
TTP (trusted third party)
TUP (telephony user part) - SS7
TX (transit exchange)
Tx/TX (transmitter - usually radio)
TXE (telephone exchange equipment)
TXT (not an acronym - a contraction of text)

U (interface standard for a pair of wires used for basic rate ISDN)
UA (user agent)
UAC (user agent client)
UAS (user agent server)
UAX (unattended automatic exchange)
UAWG (Universal Asymmetric DSL Working Group)
UBR (unspecified/uncommitted bit rate)
UCC (Uniform Code Council). External web-site.
UCD (upstream channel descriptor)
UCF (unregister confirm)
UCI (universal communications identifier)
UDDI (universal description, discovery and integration specification)
UDP (user datagram protocol)
UDU (unicast-directed update)
UE (user equipment)
UEA (UMTS encryption algorithm)
U/G (underground)
UHF (ultra high frequency)
UI (usage identification)
UIA (UMTS integrity algorithm)
UICC (universal integrated circuit card/UMTS integrated circuit card)
Um (GSM air interface)
UML (unified modelling language)
UMTS (universal mobile telephone system)
UNE-P (unbundled network element - platform)
UNI (user network interface)
UPC (usage parameter control)
UPnP (universal plug 'n play)
UPS (uninterrupted power supply)
UPT (universal personal telecommunications)
URI (uniform resource identifier)
URL (uniform or universal resource locator)
URQ (unregister request)
USB (upper sideband)
USB (universal serial bus)
USBIF (Universal Serial Bus Implementers' Forum). External web-site.
USF (universal service fund - USA)
USIM (UMTS subscriber identity module/user services identity module)
USSD (unstructured supplementary services data)
USTA (United States Telecommunications Organisation)
U-TDOA (uplink time difference of arrival)
UTP (un-screened/un-shielded twisted pair)
UTRA[N] (UMTS terrestrial radio access [network])
UU (user to user)
UWB (ultra-wideband)
UWCC (Universal Wireless Communication Consortium)
UXGA (ultra extended graphics array)

V series (ITU recommendations for data over the PSTN)
VA (validation authority)
VAD (voice activity detector)
VAN (value added network)
VAS (value added service)
VASP (value added service provider)
VB (validation broker)
VBR (variable bit rate)
VC (venture capital[ist])
VC (virtual concatenation)
VC (virtual container)
VCC (virtual channel connection)
VCI (virtual channel identification)
VCI (virtual connection identifier)
VCO (voltage controlled oscillator)
VCSEL (vertical-cavity surface emitting lasers)
VDSL (very high speed/data-rate digital subscriber loop)
VESA (Video Electronics Standards Association). External web-site.
VGA (video graphics array)
VHE (virtual home environment)
VHF (very high frequency)
VLAN/V-LAN (virtual local area network)
VLF (very low frequency)
VLL (virtual leased line)
VLR (visitor location register)
VLSI (very large scale integration)
VLSM (variable length subnet masks)
VM (virtual machine)
VoD (video on demand)
VoD (voice over data)
VoDSL (voice over DSL)
VoIP (voice over IP)
VPC (virtual path connection)
VPI (virtual path identifier)
VPIM (voice profile for Internet mail)
VPLS (virtual private LAN [local area network] service)
VPN (virtual private network)
VPT (village public telephone)
VRC (vertical redundancy checking)
VRF (virtual route forwarding)
VSAT (very small aperture terminal)
VSB (vestigial sideband)
VXML (voice extensible mark-up language)

W3C (World Wide Web Consortium). External web-site.
WAE (wireless application environment)
WAN (wide area network)
WAP (wireless application protocol)
WARC (World Administrative Radio Conference)
WATS (wide area telephone service)
WCDMA (wideband code division multiple access)
WDF (Wireless Data Forum)
WDM (wavelength division multiplex)
WDMA (wave division multiple access)
WDP (wireless datagram protocol)
WECA (Wireless Ethernet Compatibility Alliance). External web-site.
WEP (wired equivalent privacy)
WfMC (Workflow Management Coalition). External web-site.
WFQ (weighted fair queuing)
WG (working group)
WHO (World Health Organisation). External web-site.
WIA (World Internetworking Alliance).
WIN (wireless intelligent network)
WIM (wireless identity module)
WiMAX (worldwide interoperability of microwave access)
WIMP (windows, icons, mouse and pointers)
WINA (WAP [wireless access protocol] Interim Naming Authority)
WLAN (wireless local area network)
WLL (wireless local loop)
WML (wireless markup language)
WMLC (a compiled and compressed version of WML)
WORM (write once, read many-times)
WOS (wait on start)
WP (working party)
WRED (weighted random early drop)
wrt (with respect to)
WSDL (web services description language)
WSML (web services modelling language)
WSMO (web services modelling ontology)
WSP (wireless session protocol)
WSXC (wavelength selective cross connect)
WT (wireless telegraphy)
WTA (wireless telephony application)
WTLS (wireless transport layer security)
WTP (wireless transaction protocol)
WWW/www (world wide web)

X-series (ITU recommendations for data and open system communication)
XACML (extensible access control markup language)
XAML (transaction authority markup language)
XBRL (extensible business reporting language)
xDSL
xfer (transfer)
xfmr (transformer)
XGA (extended graphics array)
XHTML (extensible hypertext markup language)
XIWT (Cross Industry Working Team)
X-KISS (XML key retrieval service standard)
XKMS (XML key management specification)
X-KRSS (XML key registration service standard)
xMII (media independent interface)
xmit (transmit)
XML (extensible markup language)
XPM (cross-phase modulation)
XrML (extensible rights markup language)
XSL (XML stylesheet language)
X-TASS (XML trust assertion service specification - VeriSign)
XTP (express transfer protocol)

YTD (year to date)

ZIF (zero intermediate frequency - direct conversion receiver)
ZRP (zone routing protocol)