On Jun 18, 2011, at 5:35 PM, Daniel-Constantin Mierla miconda@gmail.com wrote:
iirc, the PRACK should follow the record-routing as part of its early dialog state. At least, from my experience the PRACKs I saw so far were sent to the proxy address due to record routing, not directly to contact address in 183. Without following the record routing, I see no way to go even for cases with NAT. For me looks like A is buggy, but I haven't checked actually the specs at this time.
Daniel,
Sorry, perhaps I was not clear. A is a softphone initiating a call through Kamailio. Kamailio forwards the call to UAS B with Record-Route header added, and UAS B sends 183s back to A through Kamailio, with 100rel Require'd. There are no RR headers seen by A, and so it does not know to send PRACK to something but the Contact in the 183.