[Freeswitch-users] Kamailio branch changes in VIA header

[Jurijs Ivolga]

Hi Sergey,

Second INVITE is because of retransmission. Probably that why there is 1 at
the end for second INVITE. That makes sense, cause when call is answered
Kamailio cancel transaction with ID
z9hG4bK5398.d5b303bd66f82a3f5cf66672ff787b76.1.

Branch parameter is identifying transaction. Bye is separate transaction
and that why it has different branch parameter. ACK is separate transaction
too, that why it has different branch parameter too.

Check image below for detailed info about transaction and dialog.

http://www.kamailio.org/pub/ser/ser-releases/0.8.12/doc/html/figures/transaction.png

With kind regards,


Jurijs

On Fri, Sep 23, 2016 at 2:09 PM, Sergey Safarov <s.safarov at gmail.com> wrote:

> Hello gys
> Could you please help me resolve issue with Kamailio.
> In attached file call from freeswitch to endpoint via Kamailio proxy.
> In packets 3 and 4 kamailio sends two INVITES with different branches in
> "VIA" header for IP 10.21.19.10 ("SIP/2.0/UDP 217.12.247.212;branch=
> z9hG4bK5398.d5b303bd66f82a3f5cf66672ff787b76.0" and "SIP/2.0/UDP
> 217.12.247.212;branch=z9hG4bK5398.d5b303bd66f82a3f5cf66672ff787b76.1").
>
> Then from endpoint Kamailio gets  100, 180 and 200 messages (packets 5, 6,
> 8, 9)  with appropriate branches in "VIA" header.
>
> Then Kamailio in packet 11 send CANCEL for branch "z9hG4bK5398.
> d5b303bd66f82a3f5cf66672ff787b76.1"
> And in packet 13 send "ACK" with new branch "SIP/2.0/UDP
> 217.12.247.212;branch=z9hG4bK5398.8ba6e3c3c63533fae1ceff3074f476fb.0"
> In packet 14 endpoint confirms CANCEL of call with branch "z9hG4bK5398.
> d5b303bd66f82a3f5cf66672ff787b76.1".
>
> And then in packet 16 strange message from Kamailio with branch
> "SIP/2.0/UDP 217.12.247.212;branch=z9hG4bK6398.
> f0bbae920c6f81401d10d39f23335696.0".
>
> Could you suggest correct answer for following questions:
>
>    1. are is kamailio incorrectly changes branch values in VIA header;
>    2. what is RFC numbers where is described proxy behavior for branch
>    value in "VIA" header.
>
>
> Sergey Safarov
>
> Interest page https://andrewjprokop.wordpress.com/2014/03/06/
> understanding-the-sip-via-header/
>
>
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