[SR-Users] Manipulate sip header on an in-dialog negative reply

Olli Attila attiolli at gmail.com
Fri Dec 14 11:31:02 CET 2018


We have a call case where our softswitch replies to in-dialog
re-invite with "SIP 491 Request pending". This happens when a customer
sip device is trying to re-invite the session too fast even though the
softswitch is still processing the earlier request. Kamailio operates
between this customer device and the softswitch.

The softswitch is adding a P-Charging-Vector header to this SIP 491
reply which we want to drop (remove_hf...)  from the reply when we
route the SIP 491 message  back to the customers device.

I tried to drop this inside in-dialog failure route but it seems that
Kamailio forwards the orginal 491 message statelessly to customer and
the header still extists there eventhough failure route has deleted
it. I guess this modification should be done in a sateful manner for
Kamailio to actually write the changes to the outgoing reply towards
the customer device.

Any suggestions how the 491 reply could be edited and then forwarded
onwards to the customer device?


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