PRACK is an in-dialog/sequential request, which will be relayed like other. So, Kamailio relays it in the same way that it supports any sequential request. Is it not necessary for a SIP proxy to do anything specific to support PRACK.
The UAC should not be increasing the CSeq when sending a PRACK. My guess is that it is the UAS which doesn't like it, rather than Kamailiio. From RFC 3262 Section 3 ("UAS Behavior"):
A matching PRACK is defined as one within the same dialog as the response, and whose method, CSeq-num, and response-num in the RAck header field match, respectively, the method from the CSeq, the sequence number from the CSeq, and the sequence number from the RSeq of the reliable provisional response.
-- Alex
On 05/13/2013 11:37 AM, Alex Solt wrote:
Hi,
Does kamailio support PRACK method ? Any configuration change is needed? It appears Kamailio does not like the PRAK when increasing Cseq. Here is the call flow:
A send INVITE --> Kamailio --> proxy the packet to B B send 180 Ringing --> Kamailio -> proxy the packet to A A send PRAK (increase Cseq) --> Kamailio --> proxy the packet to B B send 200 OK --> Kamailio -> proxy the packet to A Kamailio re-send 180 Ringing to A
Thanks, AS
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