Hello,
On 3/29/12 1:14 AM, Andreas Granig wrote:
Hi,
On 03/28/2012 06:37 PM, Iñaki Baz Castillo wrote:
2012/3/28 Min Wang<ser.ba...@gmail.com>:
In order to properly proxy the msg to GW1, Kamailio seems need to change the
to tag from B to A.
Totally wrong. Multiple (early-)dialogs are 100% valid according to
RFC 3261. If you find some SIP device failing when it receives
multiple 180/183/200 responses with different To-tag, then drop it
I recently learned that for example Siemens switches implement "Request
Disposition: no-fork" defined in http://www.ietf.org/rfc/rfc3841.txt,
and if for some reason you decide to fork nonetheless on your side,
you'd probably want to do something about the different to-tags
(although you're violating against that specific RFC then). No idea how
such a device would react to not getting a to-tag at all by stripping it
out as Klaus suggested in another response, but at least that Siemens
switch doesn't bail out on getting different to-tags in provisional replies.
I fully agree that devices not supporting multiple to-tags in
provisional replies should be dropped, it will make life easier for
everyone.
Regarding hacks to make an workaround, in many cases I saw devices
requiring to-tag in 183. In that case, a solution can be dropping 183
from reply route and send 180 instead with t_reply(...).
Cheers,
Daniel
--
Daniel-Constantin Mierla
Kamailio Advanced Training, April 23-26, 2012, Berlin, Germany
http://www.asipto.com/index.php/kamailio-advanced-training/
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