The following are two rfc3261 snippets which indicate that the Contact is mandatory for dialog creating 18x responses. Section 12.1: "Dialogs are created through the generation of non-failure responses to requests with specific methods. Within this specification, only 2xx and 101-199 responses with a To tag, where the request was INVITE, will establish a dialog." Section 12.1.1: "When a UAS responds to a request with a response that establishes a dialog (such as a 2xx to INVITE)" ... "The UAS MUST add a Contact header field to the response."
________________________________________ From: Iñaki Baz Castillo [[email protected]] Sent: Wednesday, July 27, 2011 10:27 AM To: Brett Tate Cc: [email protected] Subject: Re: [Sip-implementors] BYE before call answer 2011/7/27 Brett Tate <[email protected]>: > Concerning the lack of Contact within a dialog created by an INVITE 18x with > To tag, it means that the UAS is non compliant to RFC 3261. I don't agree. RFC 3261 states that Contact MUST be present in *reliable* responses (not final I mean), and RFC 3261 just defines 2XX as reliable. 180/183 are not reliable so the don't require to contain Contact header. Just in case PRACK is used for 180/183 responses it's required that such responses contain Contact (and mirror Record-Route). -- Iñaki Baz Castillo <[email protected]> _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
