Hello, I'm a voip specialist with over 10 years of experience working on the TS department of a Voip company; I can install, troubleshoot and customize many VOIP devices including : softphones, ATAs, IP-phones and PBX systems like Asterisk/FPBX. I read your project description, and I can help you fix your SIP header issue. You may contact me through chat at any time.
Thank you.