The Session Initiation Protocol (SIP) is a communications protocol for signaling and controlling multimedia communication sessions. It is designed to be used over IP networks and can be used to establish, modify, and terminate sessions for a variety of media types, including voice, video, and data.
SIP is a text-based protocol that uses a request-response model. A SIP request is sent by a client to a server, and the server responds with a SIP response. The SIP request can contain information about the session, such as the participants, the media types, and the desired quality of service. The SIP response can contain information about the status of the session, such as whether it was successful or not.