The terms "IP telephony" and "voice over IP" (VoIP) are synonymous. However, the term VoIP is widely used for the actual services offered (see VoIP for details), while IP telephony often refers to ...

The primary IP telephony signaling protocols are H.323, SIP and MGCP/MEGACO. There are also proprietary protocols; for example, Cisco's Skinny is widely used. See IP telephony. THIS DEFINITION IS ...

but Microsoft is shaking up that model by saying forget about having a separate proprietary PBX and IP telephony server, just buy OCS, which provides the same capabilities at less cost,” said ...