Reason Header

Since it is (often) useful to know why a Session Initiation Protocol (SIP) request was issued, the Reason header was introduced. It encapsulates a final status code in a provisional response.

This functionality was needed to resolve the "Heterogeneous Error Response Forking Problem" (HERFP).

For details see RFC 3326.

Slide Notes

H. Schulzrinne, D. Oran, and G. Camarillo, “The Reason Header Field for the Session Initiation Protocol (SIP)”, IETF RFC 3326, December 2002 ftp://ftp.rfc-editor.org/in-notes/rfc3326.txt Links to an external site.

Transcript

[slide338] So we could have a reason header.