[SR-Users] Handling Cancel with rewritten To: and From: headers

Jeremya jeremy at electrosilk.net
Tue Mar 29 06:52:03 CEST 2011


Hi,

I have a kamailio 3.1.0 system.

I am using mostly the kamailio.cfg script that came with that release
but I've made a couple of changes

- The pstn.gw_ip bit doesn't work - syntax error - so I've substituted
fixed text for now
- I've expanded the PSTN section to IN_PSTN and OUT_PSTN to handle
outgoing PSTN calls and route PSTN incoming calls to the correct phones.
- As (strange) requirement of my SIP trunk provider I've had to rewrite
the To: and From: headers on new outgoing PSTN calls

The issue I have is with CANCEL. I'm using the default CANCEL handling
stanza in kamailio.cfg

# CANCEL processing
if ( is_method ( "CANCEL" ) )
{
  if ( t_check_trans() )
    t_relay();
  exit;
}

What I see in wireshark is that the From: header is the same as my
rewritten version, but the To: header is as provided by the UA
This doesn't cause any real problems but I'd like to know what the rules
are for kamailio rewriting a CANCEL message - and if required - whether
I can rewrite a header in the CANCEL section and not have it 'adjusted'
by the internal t_check_trans and t_relay logic?

Thanks

Jeremy





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