> But as Vikram pointed out that contact header is an optional header > in 1xx responses.
The example indicates that the 18x with To tag (and without Contact) was the dialog forming response. Thus the Contact header is not optional. The following are two rfc3261 snippets which indicate that the Contact is mandatory for such 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." _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
