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<body class='hmmessage'><div dir='ltr'>Just to confirm:<div>Kamaili is forwarding the PRAK packet. However, it seems the kamailio ignore the Cseq increase within the PRAK and therefore it ignore the 200 Ok after that. Then, Kamailio re-send 180 again.</div><div><br></div><div>Thank,</div><div>AS</div><div><br><div><div id="SkyDrivePlaceholder"></div>> Date: Mon, 13 May 2013 11:41:09 -0400<br>> From: abalashov@evaristesys.com<br>> To: sr-users@lists.sip-router.org<br>> Subject: Re: [SR-Users] Does Kamailio support PRACK ?<br>> <br>> PRACK is an in-dialog/sequential request, which will be relayed like <br>> other. So, Kamailio relays it in the same way that it supports any <br>> sequential request. Is it not necessary for a SIP proxy to do anything <br>> specific to support PRACK.<br>> <br>> The UAC should not be increasing the CSeq when sending a PRACK. My <br>> guess is that it is the UAS which doesn't like it, rather than <br>> Kamailiio. From RFC 3262 Section 3 ("UAS Behavior"):<br>> <br>> A matching PRACK is defined as one within the same<br>> dialog as the response, and whose method, CSeq-num, and<br>> response-num in the RAck header field match, respectively,<br>> the method from the CSeq, the sequence number from the CSeq,<br>> and the sequence number from the RSeq of the reliable<br>> provisional response.<br>> <br>> -- Alex<br>> <br>> On 05/13/2013 11:37 AM, Alex Solt wrote:<br>> <br>> > Hi,<br>> ><br>> > Does kamailio support PRACK method ? Any configuration change is needed?<br>> > It appears Kamailio does not like the PRAK when increasing Cseq.<br>> > Here is the call flow:<br>> ><br>> > A send INVITE --> Kamailio --> proxy the packet to B<br>> > B send 180 Ringing --> Kamailio -> proxy the packet to A<br>> > A send PRAK (increase Cseq) --> Kamailio --> proxy the packet to B<br>> > B send 200 OK --> Kamailio -> proxy the packet to A<br>> > Kamailio re-send 180 Ringing to A<br>> ><br>> ><br>> > Thanks,<br>> > AS<br>> ><br>> ><br>> ><br>> > _______________________________________________<br>> > SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list<br>> > sr-users@lists.sip-router.org<br>> > http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users<br>> ><br>> <br>> <br>> -- <br>> Alex Balashov - Principal<br>> Evariste Systems LLC<br>> 235 E Ponce de Leon Ave<br>> Suite 106<br>> Decatur, GA 30030<br>> United States<br>> Tel: +1-678-954-0670<br>> Web: http://www.evaristesys.com/, http://www.alexbalashov.com/<br>> <br>> _______________________________________________<br>> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list<br>> sr-users@lists.sip-router.org<br>> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users<br></div></div> </div></body>
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