> 18x from B side received without contact header. > 18x response has "To tag" and without Record Route.
Per RFC 3261 section 12.1, the To tag within 101-299 response (to dialog creating request) creates the dialog. If the required Contact is missing, it is a malformed message. Since malformed, the UAC can basically act however it desires. As mentioned within https://lists.cs.columbia.edu/pipermail/sip-implementors/2008-August/020062.html, there numerous ways the UAC can handled the malformed 18x. The UAC does not know why malformed: 1) first 1xx dropped, 2) pre-rfc3261 implementation, 3) bad implementation, or 4) locally forgotten early dialog. If the UAC assumes number 2 is appropriate, it flows the rules prior to rfc3261 which allowed the Contact to be optional. _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
