Voice over IP

Voice over Internet Protocol, also called VoIP, IP Telephony, Internet telephony, Broadband telephony, Broadband Phone and Voice over Broadband is the routing of voice conversations over the Internet or through any other IP-based network. Companies providing VoIP service are commonly referred to as providers, and protocols which are used to carry voice signals over the IP network are commonly referred to as Voice over IP or VoIP protocols. They may be viewed as commercial realizations of the experimental Network Voice Protocol (1973) invented for the ARPANET providers. Some cost savings are due to utilizing a single network to carry voice and data, especially where users have existing underutilized network capacity that can carry VoIP at no additional cost. VoIP to VoIP phone calls are sometimes free, while VoIP to public switched telephone networks, PSTN, may have a cost that is borne by the VoIP user.
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<communications> (VoIP) Any technology providing voice telephony services over IP, including CODECs, streaming protocols and session control. The major advantage of VoIP is lower cost, by avoiding dedicated voice circuits.
Currently VoIP is being deployed on internal corporate networks, and, via the Internet, for low cost (and low quality) international calls. It is also used for telephony applications such as voice and fax mail.
The ITU standard is H.323, which is a whole suite of protocols, while the IETF has developed the much simpler SIP to solve the session control problem and MGCP/Megaco to solve the gateway problem.
(2003-11-30)