VoIP abbreviations

Abbr.	Meaning
A/D	Analog-to-digital converter
CO	Central Office or telephone exchange
D/A	Digital-to-analog converter
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
FXO	Foreign exchange station
FXS	Foreign exchange office
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
PABX	Private automatic branch exchange - See PBX
PBX	Private branch exchange - A privat telephone exchange
POTS	Plain old telephone service
PSTN	Public Switched Telephone Network
Q.931	Q.931 is the ITU standard ISDN connection control signalling protocol
T1	T1 carrier used to carry ISDN PRI between Telco and customer in USA/Japan
Telco	Telephone company
VoIP	Voice over IP