[OpenSIPS-Users] why is a new dialog being created mid-call for an INFO message?

[R.P. Aditya]

Hi,

I'm running kamailio with a fairly vanilla setup (no NAT, no accounts)
with very small variation to the default config and it works well 99.99%
of the time!

A few days ago, I found that calls to a certain destination (A Cisco
MCU) would establish and work until the remote end sent an in-dialog
SIP INFO message (same call-id):

         Call-ID: df100a80-1ad1f5f2-159de-a9086cc6 at x.y.z.a
         CSeq: 1 INFO
             Sequence Number: 1
              Method: INFO

and kamailio would treat it as a new dialog and spawn a new call, which
during a transient failover got sent to the backup PBX which would
reply that there was no such call and the call would be dropped.

I've tried to look through the dialog module and the configuration to
see why kamailio would treat this in-dialog SIP INFO message as part of
a new call -- is it because the sequence number is "1" ? (it is the
first INFO message in the dialog and the call-id matches, so that
shouldn't be it)

Any hints on how I can troubleshoot (I've tried tracing it via the
config file to no avail)?

Thanks,
Adi