RFC Errata
RFC 5589, "Session Initiation Protocol (SIP) Call Control - Transfer", June 2009
Source of RFC: IETF - NON WORKING GROUPArea Assignment: rai
Errata ID: 3273
Status: Held for Document Update
Type: Technical
Publication Format(s) : TEXT
Reported By: Victor S. Osipov
Date Reported: 2012-06-29
Held for Document Update by: Robert Sparks
Section 5 says:
3. There were concerns with authorizing out-of-dialog REFERs. The authorization policy for REFER in most implementations piggybacks on the authorization policy for INVITE (which is, in most cases, based simply on "I placed or answered this call"). Globally Routable UA URIs (GRUUs) [SIP-GRUU] can be used to address problem 1. Problem 2 can be addressed using the Target-Dialog header field defined in [RFC4538]. In the immediate term, this solution to problem 2 allows the existing REFER authorization policy to be reused.
It should say:
3. There were concerns with authorizing out-of-dialog REFERs. The authorization policy for REFER in most implementations piggybacks on the authorization policy for INVITE (which is, in most cases, based simply on "I placed or answered this call"). Globally Routable UA URIs (GRUUs) [SIP-GRUU] can be used to address problem 1. Problem 2 can be addressed using the Target-Dialog header field defined in [RFC4538]. In the immediate term, this solution to problem 2 allows the existing INVITE authorization policy to be reused by REFER (thus solving problem 3).
Notes:
The phrase 'allows the existing REFER authorization policy to be reused' leads to a misunderstanding and confusion, because in actual fact INVITE authorization policy may be reused by REFER, not inversely.
The correction is proposed in order to clear up confusion.