VoIP abbreviations

Abbr.	Meaning
A/D	Analog-to-digital converter
CFB	Call Forwarding Busy
CFNR	Call Forwarding No Reply
CFU	Call forwarding Unconditional
CLIP	Calling Line Identification Presentation
CLIR	Calling Line Identification Rejection
CO	Central Office or telephone exchange
D/A	Digital-to-analog converter
DECT	Digital Enhanced Cordless Telecommunications
DND	Do Not Disturb
DSP	Digital signal processor
DTMF	Dual-tone multi-frequency signaling
E1	E1 carrier used to carry ISDN PRI between Telco and customer in Europe
E.164	E.164 is a international public telecommunication numbering plan used in the PSTN
ETSI	European Telecommunications Standards Institute
FXO	Foreign exchange station
FXS	Foreign exchange office
H.323	ITU VoIP signaling protocol suite
ISDN	Integrated Services Digital Network
ISDN BRI	ISDN Basic Rate Interface. 2 B channels and 16 Kbps D channel
ISDN PRI	ISDN Primary Rate Interface. 30 B channels and 64 Kbps D channel in Europe
ITU	International Telecommunication Union
ITU-T	ITU Telecommunication Standardization Sector
IVR	Interactive Voice Response
MOH	Music on hold
PABX	Private automatic branch exchange - See PBX
PBX	Private branch exchange - A privat telephone exchange
PoE	Power over Ethernet
POTS	Plain old telephone service
PSTN	Public Switched Telephone Network
Q.931	Q.931 is the ITU standard ISDN connection control signalling protocol
QSIG	ISDN based signaling protocol for signaling between PBXs
SIP	Session Initiation Protocol An IETF VoIP Signaling protocol
T1	T1 carrier used to carry ISDN PRI between Telco and customer in USA/Japan
Telco	Telephone company
UA	User agent In SIP the IP phones are called User agents
VoIP	Voice over IP