From: "B Venkat S.R Swamy" <[EMAIL PROTECTED]> I am sorry for that confusing statements, let me correct and clarify it as follows:
1> Invite sent to the network 2> 1xx response to Invite received from network without any Contact header. Dialogue gets established. Such a 1xx response is incorrect. >From a practical point of view, it is incorrect because it would cause the creation of an early dialog, but the UAC would not know the contact address of the UAS. This results in the difficulties you have enumerated. >From a standards point of view, see these sections of RFC 3261: 13.3.1.1 Progress If the UAS is not able to answer the invitation immediately, it can choose to indicate some kind of progress to the UAC (for example, an indication that a phone is ringing). This is accomplished with a provisional response between 101 and 199. These provisional responses establish early dialogs and therefore follow the procedures of Section 12.1.1 in addition to those of Section 8.2.6. 12.1.1 UAS behavior When a UAS responds to a request with a response that establishes a dialog (such as a 2xx to INVITE), the UAS MUST [...]. The UAS MUST add a Contact header field to the response. The Contact header field contains an address where the UAS would like to be contacted for subsequent requests in the dialog [...]. Dale _______________________________________________ Sip mailing list https://www1.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
