External CID on Call Forward

Our SIP Trunk provider only allows CIDs for numbers they have provided as DDIs, so I can’t send the original callers ID when an extension is in Call Forward to an external number (i.e. Cell Phone).

On the trunk I have set the CID Option to Block Foreign CIDs. On the help for that option it says the CID for the extension/user will be sent instead, but this is not what is happening. It is sending the CID defined for the trunk.

This is causing an issue as the recipient of the received call cannot tell if it is a forwarded call or just a general call from the office.

The Outbound CID for the extension is set correctly, and appears on calls from that extension to the outside.

Is there another option I need to set somewhere to make it use the forwarded extensions CID rather than the Trunk one? I have had a look through advanced options but nothing jumps out.

I am using FreePBX 2.11 and Asterisk 11.12.0