IP PBX

An IP PBX is a business telephone system designed to deliver voice or video over a data network and interoperate with the normal Public Switched Telephone Network (PSTN).

VoIP gateways can be combined with traditional PBX functionality enabling businesses to use their managed intranet to help reduce long distance expenses, enjoy the benefits of a single network for voice and data and advanced CTI features or be used on a pure IP system which in most cases give greater cost savings, greater mobility, and increased redundancy.An IP-PBX can exist as a hardware object, or virtually, as a software system.  Because a major part of IP PBX functionality is provided in software, it is relatively inexpensive and easy to add additional functionality, such as conferencing, control of live calls, Interactive voice response IVR, TTS/ASR text to speech/automatic speech recognition, Public switched telephone network interconnection ability supporting both analog and digital circuits, Voice over IP protocols including SIP, Inter-Asterisk eXchange, H.323, Jingle extension of XMPP protocol introduced by Google Talk and others.

via IP PBX – Wikipedia, the free encyclopedia.