[SR-Users] Kamailio: 500 Server error occurred (19/SL).

Hello guys, I have strange behavior on my Kamailio-1.5.1-notls instance. I have LCR and TM modules enabled.For a particular destination I have 4 routes to try. When I call to non-existing number, it tries - route 1 (404 Not Found) - route 2 (404 Not Found) - route 3 (503 Service unavailable) And the problem is with the last 503. Kamailio ACKs it, immediately drops these 2 lines into syslog Jul 13 04:14:47 /usr/local/sbin/kamailio[23572]: ERROR:tm:t_forward_nonack: no branch for forwarding Jul 13 04:14:47 /usr/local/sbin/kamailio[23572]: ERROR:tm:w_t_relay: t_forward_nonack failed And sends SIP/2.0 500 Server error occurred (19/SL). To the call originator. 30 microseconds later it sends SIP/2.0 500 Service Unavailable. to the originator again Latter 500 looks like the relayed original "503 Service unavailable". I think so because the Reason header is the same: Reason: SIP;cause=503;text="Service Unavailable";icodetext="NoCircuitAvailable";iintcode=10034;isubsystem=3. Obviously call is terminated. I noticed that that last peer rewrites my Via headers like this: Original: == Via: SIP/2.0/UDP 187.45.214.132;branch=z9hG4bK3dac.fae9b793.2. Via: SIP/2.0/UDP 192.168.2.33:5622;received=49.49.59.23;branch=z9hG4bK-d8754z-a6ba40014f97fb7c-1---d8754z-;rport=23832. == Rewritten == Via: SIP/2.0/UDP 187.45.214.132;received=187.45.214.132;branch=z9hG4bK3dac.fae9b793.2,SIP/2.0/UDP 192.168.2.33:5622;received=49.49.59.23;branch=z9hG4b == I tried to modify via1_matching parameter (1 -> 0) but no changes. My questions are: - What can be the reason of that 500 with 19/SL - Can kamailio properly handle this 1 line Via header? - What can be the reason of that "t_forward_nonack: no branch for forwarding"? Regards, Max