Summary of Session Initiation Protocol (SIP)

Session Initiation Protocol (SIP) is a protocol used for initiating, maintaining, and terminating real-time sessions that involve voice, video, messaging, and other communications applications. It is defined in RFC 3261.

SIP is an application-layer protocol that follows a client-server architecture model. SIP messages are typically carried over the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP).

SIP messages are text-based and include headers and a message body. The headers contain information such as the SIP version, the method used, and the addresses of the sender and receiver. The message body can contain data such as the session description or the message content.

SIP transactions are used to represent the interactions between SIP entities. Transactions can be either client transactions or server transactions.

SIP call flow refers to the sequence of messages exchanged between SIP entities to establish and terminate a call. The call flow typically includes session initiation, confirmation, modification, and termination.

SIP includes several security mechanisms such as Transport layer security (TLS), Secure Real-time Transport Protocol (SRTP), and Digest authentication.

Overall, SIP is a powerful protocol for initiating, maintaining, and terminating real-time sessions, and it is widely used in VoIP networks.

Sources:

• RFC 3261: https://datatracker.ietf.org/doc/html/rfc3261
• Today's date: 2023-05-10