Hello,

the CANCEL to be sent is generated locally by tm module from the INVITE that was sent on the branch, so the errors is actually about a duplicate To header in that INVITE. Check it on the network to see if that's the case.

Cheers,
Daniel

Hello,

We are having an issue here where Kamailio is complaining about duplicate To header, while in the SIP Packet there is just one. See below the log message:

DEBUG: tm [t_msgbuilder.c:391]: build_local_reparse(): duplicate To header

ERROR: tm [t_msgbuilder.c:531]: build_local_reparse(): cannot build CANCEL request
ERROR: tm [t_cancel.c:297]: cancel_branch(): attempt to build a CANCEL failed
ERROR: tm [t_fwd.c:1434]: e2e_cancel(): cancel error

And this is the sip message:

CANCEL sip:123456789@1.2.3.4:5060 SIP/2.0
Via: SIP/2.0/UDP 192.168.1.1:19373;branch=z9hG4bK-524287-1---7774073fad1a3264;rport
Max-Forwards: 70
To: <sip:123456789@1.2.3.4:5060>
From: "101"<sip:101@1.2.3.4:5060>;tag=6f373b66
Call-ID: hC2O6zx8ZaUJ1di046
CSeq: 2 CANCEL
Proxy-Authorization: Digest username="101",realm="1.2.3.4",nonce="YJKbfWCSmlFTHxdJfKmySydF9L7FzfaqcgyOo4A=",uri="sip:123456789@1.2.3.4:5060",response="2bf2ba8ef2374d6aa8c39d650613077d",algorithm=MD5
User-Agent: TEST
Content-Length: 0

version: kamailio 5.5.0 (x86_64/linux) d4c1a1

The route itself, is like in the standard documentation:

# CANCEL processing
          if KSR.is_CANCEL() :
              KSR.info(RANDOM_LOG + 'KSR.is_CANCEL')
              if KSR.tm.t_check_trans()>0 :
                  self.ksr_route_relay(msg)
              return 1

   def ksr_route_relay(self, msg):
        if KSR.is_method_in("IBSU") :
            if KSR.tm.t_is_set("branch_route")<0 :
                KSR.tm.t_on_branch("ksr_branch_manage")

        if KSR.is_method_in("ISU") :
            if KSR.tm.t_is_set("onreply_route")<0 :
                KSR.tm.t_on_reply("ksr_onreply_manage")

        if KSR.is_INVITE() :
            if KSR.tm.t_is_set("failure_route")<0 :
                KSR.tm.t_on_failure("ksr_failure_manage")

        if KSR.tm.t_relay()<0 :
            KSR.sl.sl_reply_error()

        return -255

Thanks

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