On Tue, 2009-02-10 at 11:56 -0500, Bob Penfield wrote: > The text in 8.1.3.5 means that the From and To headers in the new > INVITE should have the same value including tags as the rejected > INVITE. If it was an initial (out-of-dialog) INVITE, there will be no > to-tag in the To, and thus the re-submitted request will not have a > to-tag either. There is no need to change the Call-ID or the from tag > because no dialogs were created. > > If it is an in-dialog request, it must have the same tags otherwise it > will not match the dialog. This could happen if authentication is > required for in-dialog requests and the UAC did not include the > credentials, or the credentials are stale. > > From an implementation point of view, it is simpler if the procedures > for re-submitting requests for repairable 4xx errors are the same for > in-dialog and out-of-dialog requests. > > I see no reason to change the Call-ID or from tag.
All of the above matches my understanding and the discussions that I've seen here. > As for the question "If the From tag doesn't change, can the UAS > retrain the same To tag as well?", I would say that UAS should not use > the same to-tag for a new request. I'm sure that the UAS should not use the same to-tag in its response to the new request -- the first request did not establish a dialog, so the second request could not be part of that dialog. And indeed, it would be difficult to build a UAS that did use the same to-tag, as it would have to remember the to-tag it used in the first request and use it in the second -- but nonetheless, if it received two copies of the first INVITE and rejected both, it would have to use different to-tags for the two error responses. Dale _______________________________________________ Sip mailing list https://www.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
