[SR-Users] Does Kamailio support PRACK ?

[Alex Solt]

Just to confirm: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.
Thank,AS
> Date: Mon, 13 May 2013 11:41:09 -0400
> From: abalashov at evaristesys.com
> To: sr-users at lists.sip-router.org
> Subject: Re: [SR-Users] Does Kamailio support PRACK ?
> 
> 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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> >
> 
> 
> -- 
> Alex Balashov - Principal
> Evariste Systems LLC
> 235 E Ponce de Leon Ave
> Suite 106
> Decatur, GA 30030
> United States
> Tel: +1-678-954-0670
> Web: http://www.evaristesys.com/, http://www.alexbalashov.com/
> 
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