What is SIP?
SIP stands for Session Initiation Protocol and is a communications protocol for starting (signalling) and managing multimedia, including voice, video, and data, sessions between IP end points and is most commonly used in Voice over IP telephony systems. SIP consists of 3 distinct components:
Firstly, there is Session Initiation, which as the term suggests, is the starting point of a SIP-based communication session.
Next, we have the Session Description Protocol (SDP) which provides a description of the session, for example which codecs are to be used, which port should be used and so on.
The final part of a SIP session is the payload. This refers to the protocol for delivering content (voice, video, data), i.e. real-time transport protocol (RTP) / secure real-time transport protocol (sRTP).
