Hello, 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? Cheers, --Olli