SIP Extension RFCs
Identity, transfer and refer
- RFC 3325 - Private Extension for Asserted Identity within Trusted Networks (P-Asserted-Identity)
- RFC 3515 - The Session Initiation Protocol (SIP) Refer Method (REFER, Refer-To)
- RFC 3891 - The Session Initiation Protocol (SIP) "Replaces" Header
- RFC 3892 - The Session Initiation Protocol Referred-By mechanism
- RFC 4244 - An extension to Session Initiation Protocol (SIP) for required History Information
Signaling and headers
- RFC 3326 - The Reason Header Field for the Session Initiation Protocol (SIP) (often used with Q.850 cause codes; see RFC 6432)
- RFC 3311 - The Session Initiation Protocol (SIP) UPDATE Method (session parameter changes without re-INVITE)
- RFC 4028 - Session Timers in the Session Initiation Protocol (SIP) (Session-Expires, Min-SE)