I am having a particular billing issue with my SIP trunk provider with regards to external calls that are forwarded out to external destinations. After discussing the issue with my provider, the solution we came up with is this: in the INVITE SIP header for the call going from my server to the forward destination, I need the SIP From: header to have the DID of the trunk. For the Remote-Party-ID header, I need to caller id of the original caller.
I have tried sendrpid=yes and trustrpid=yes, but that just assigns the caller ID of the original caller to both the From and the RPID header, as designed. If I set the trunk to “Block Forign CIDs,” then even with sendrpid, it sets the trunk’s DID (it’s caller ID) as both the From and RPID header.
I am honestly not sure where to start looking next.
FreePBX distro version 12.7.6-1910-1.sng7, FreePBX version 18.104.22.168 (Yea, I know), Asterisk 16.6.2