(Internet Protocol Private Branch eXchange) A telephone switch that supports voice over IP (VoIP). IP PBXs convert IP phone calls into traditional circuit-switched TDM connections for the PSTN. They also support traditional analog and digital telephones, allowing enterprises to migrate slowly to an all-IP telephony environment. See IP telephony and PBX.
IP PBXs and TDM PBXs
This illustration contrasts a traditional PBX and an IP PBX that serves IP phones only. In practice, IP PBXs also support legacy telephones.
