Hi I've been all over forums, the wiki, mailing lists but I just can't find the answer to my problem. Perhaps the reason why I don't get the answer is that I don't properly understand what to search for? ;-) Any way. The problem I'm facing is that I have to present the Via: string in the INVITE in a specific manner to successfully setup my SIP trunk to a SIP enabled Siemens MSC. It should be presented as follows: INVITE sip:xxxxxxxxxxxx@<IP_ADDRESS>:5060 SIP/2.0 Via: SIP/2.0/UDP <IP_ADDRESS:5060>;rport;branch=z9hG4bKQ96vgD8Z1c2rN How can I force the :5060 in the Via: uri? Before I forget. The server is all running on Public IP's except to this specific trunk. In this scenario FS is a Full-ON SBC handling media in Full Proxy. Thank you very much Kind Regards Sent from my iPhone