Session Initiation Protocol

Definition: SIP - Session Initiation Protocol - is a network communications protocol commonly employed for Voice over IP (VoIP) signaling. In VoIP networking, SIP is an alternative approach to signaling using the H.323 protocol standards.

SIP is designed to support the calling features of traditional telephone systems. However, unlike the traditional SS7 technology for telephone signaling, SIP is a peer-to-peer protocol.

SIP is also a general-purpose protocol for multimedia communications not limited to voice applications.