21CN	BT's 21st Century Network
ACD	Automatic Call Distribution
ADC	Analogue–Digital Convertor
ADSL	Asymmetrical Digital Subscriber Line
ADPCM	Adaptive Differential Pulse Code Modulation
AMPS	Advanced Mobile Phone System
ANI	Automatic Number Identification
API	Application Programming Interface
ARS	Automatic Route Selection
ASCII	American Standard Code for Information Interchange
ATM	Asynchronous Transfer Mode
BER	Bit Error Rate
BHCA	Busy Hour Call Attempts
BHCC	Busy Hour Call Completions
BRA / BRI	ISDN Basic Rate Access / Interface
BTNR	BT Network Requirement
CCS	Centi-Call Seconds
CCITT	Comité Consultatif International Télégraphique et Téléphonique
CDR	Call Detail Recording / Record
CLI	Calling Line Identity
CMS	Call Management System
CO	Central Office
CoS	Class of Service
COTS	Commercial Off-The-Shelf
CP	Communications Provider
CPE	Customers' Premises Equipment
CPS	Carrier Pre-Selection
CRC	Cyclic Redundancy Check
DAC	Digital–Analogue Convertor
DACS	Digital Access Carrier System
DASS	Digital Access Signalling System
DCE	Data Communications Equipment
DDF	Digital Distribution Frame
DDI	Direct Dialling In
DECT	Digital Enhanced Cordless Telecommunications
DID	Direct Inward Dialling
DND	Do Not Disturb
DNIS	Dialled Number Identification Service
DNS	Domain Name System / Server
DPNSS	Digital Private Network Signalling System
DSL	Digital Subscriber Line
DTE	Data Terminal Equipment
DTMF	Dual-Tone Multi-Frequency
DTT	Digital Terrestrial Television
DVB	Digital Video Broadcasting
DWDM	Dense Wavelength Division Multiplex
EDGE	Enhanced Data rates for GSM Evolution
EDI	Electronic Data Interchange
ENUM	Electronic Numbering
FDM	Frequency Division Multiplex
FTTC	Fibre To The Cabinet
FTTP	Fibre To The Premisess
FX	Foreign Exchange
GPRS	General Packet Radio Service
GSM	Global System for Mobile communications
HSDPA	High Speed Downlink Packet Access
HSUPA	High Speed Uplink Packet Access
HTTP	Hyper Text Transfer Protocol
IC	Integrated Circuit
ICT	Information & Communications Technology
IDC	Insulation Displacement Connection / Connector
IETF	Internet Engineering Task Force
INMARSAT	International Maritime Satellite Organization
INTELSAT	International Telecommunications Satellite Organization
IMS	IP Multimedia Subsystem
IN	Intelligent Network
IP	Internet Protocol
ISDN	Integrated Services Digital Network
ISO	International Standards Organisation
ISP	Internet Service Provider
ITU	International Telecommunications Union
IVR	Interactive Voice Response
LAN	Local Area Network
LASER	Light Amplification by the Stimulated Emission of Radiation
LEC	Local Exchange Carrier
LED	Light-Emitting Diode
LLU	Local Loop Unbundling
LTE	Long-Term Evolution
MAC	Media Access Control
MACs	Moves, Adds & Changes
MDF	Main Distribution Frame
MNO	Mobile Network Operator
MPLS	Multi-Protocol Label Switching
NAT	Network Address Translation
NCoP	Networking Code of Practice
NGN	Next Generation Network
NSE	Night Service Extension
NTE	Network Termination Equipment
OAM	Operations Administration and Maintenance
OMTP	Open Mobile Terminal Platform
OSI	Open Systems Interconnection
PABX	Private Automatic Branch Exchange
PBX	Private Branch Exchange
PC	Personal Computer
PAM	Pulse Amplitude Modulation
PCM	Pulse Code Modulation
PWM	Pulse Width Modulation
PCP	Primary Cross-connection Point
PDH	Plesiochronous Digital Hierarchy
ppm	pence per minute
PPP	Point-to-Point Protocol
PPPoA	PPP over ATM
PPPoE	PPP over Ethernet
PRA / PRI	ISDN Primary Rate Access / Interface
PSTN	Public Switched Telephone Network
PTO	Public Telecommunications Operator
QAM	Quadrature Amplitude Modulation
QoS	Quality of Service
RADIUS	Remote Authentication Dial-In User Service
RAID	Redundant Array of Inexpensive Disks
RAM	Random Access Memory
RISC	Reduced Instruction Set Computer
ROM	Read-Only Memory
SAR	Specific Absorption Rate
SCSI	Small Computer System Interface
SDH	Synchronous Digital Hierarchy
SDSL	Symmetrical Digital Subscriber Line
SFP	Small Form-Factor Pluggable
SIP	Session Initiation Protocol
SMDR	Station Message Detail Recording
SMS	Short Message Service
SP	Service Provider
SPC	Stored Program Control
SS7	Signallling System Nº 7
T&M	Time and Materials
TACS	Total Access Communication System
TCP	Transmission Control Protocol
TDM	Time Division Multiplex
ToS	Type of Service
UDP	User Datagram Protocol
UMTS	Universal Mobile Telecommunications System
UPS	Uninterruptible Power Supply
VC	Virtual Circuit [ATM]
VLAN	Virtual LAN [ATM]
VoIP	Voice over Internet Protocol
VoLTE	Voice over LTE
VP	Virtual Path [ATM]
VPN	Virtual Private Network
WAN	Wide Area Network
WAP	Wireless Application Protocol
WATS	Wide-Area Telephone Service
WDM	Wavelength Division Multiplex