On Thu, 2009-03-05 at 08:16 +0000, Elwell, John wrote: > What about non-INVITEs? Provisional responses are designed for INVITEs > and I am not certain about their applicability to non-INVITEs.
Yes, provisional responses to non-INVITEs may be slightly out of specification, but I don't expect any SIP element to malfunction if it receives a provisional response to a non-INVITE request. OTOH, I would expect most uses of 'trace' to be attached to INVITEs, although that makes me think that tracing an OPTIONS might be a useful test tool. (Which leads to an unexpected observation: RFC 3261 presupposes that all non-INVITE responses are processed promptly, but in the face of transport errors, this is not always so. In sipX, we've adjusted transaction handling so that if a re-send of a non-INVITE message is seen the recipient sends a 100 to quench further re-sends. It seems to work exactly as expected, and noticeably reduces re-sends in situations with transport errors.) > In the case of INVITE, what about Contact? Is it permissible to send a > 1xx (other than 100) without a Contact URI? RFC 3261 seems to indicate > it is optional in a 1xx, but that might be solely to cater for omission > in 100. The Contact value of a 170 should never be used, so it doesn't really matter if one is provided, or if it is usable. OTOH, every SIP element should be able to create a usable Contact URI. 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
