Introduction to VoIP

Voice over IP (VoIP) enables IP networks to provide voice services such as plain old telephone service (POTS). In VoIP, the voice gateway encapsulates voice signals into packets to transmit. IP telephony is a typical VoIP application.

Interworking between PSTN and IP is implemented through VoIP gateways. VoIP meets the commercial requirements for PC-to-telephone, telephone-to-PC, and telephone-to-telephone technologies.

H.323 and Session Initiation Protocol (SIP) are two common protocols used in VoIP. For information about H.323 and SIP, see "Voice protocols."