[Freeswitch-users] Kamailio branch changes in VIA header

[Sergey Safarov]

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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