Hi, users. Sorry about my poor english. I am a beginner of FS. I have a problem with IP-PBX. My customer wants to call mobile phone using FS connected IP-PBX. IP-PBX must set 100-rel mode. IP-PBX send to FS with custom SIP header(P-Charging-Vector), and I want to add this header to response SIP message. I read FS wiki and try many cases. but, i can't solve my problem. Follow is my call diagram: ======================================================================================================= SIP CLIENT : FreeSwitch : IP-PBX : Telecom(?) ======================================================================================================= INVITE --> <-- 100 TRYING INVITE --> <-- 100 TRYING <-- *183 Session Progress (with P-Charging-Vector Header)* *PRACK --> (without P-Charging-Vector Header) * <-- 183 (with P-Charging-Vector Header) *<-- 481 Call Leg/Transaction Does Not Exist * CANCEL --> <-- 200 OK <-- 487 Request Terminated ACK --> <-- 480 Temporarily Unavailable ACK --> ======================================================================================================= SIP Client is sofia based windows client. Please help me. Thank you. Regards, -- BooKyung Oh