Hello everyone,

A phone with enabled "Forward All" to a external mobile number, that receives a call will forward the call to the set external number, but the CID shown will be the number of the phone with enabled forward, not the original number that called it.
I want the forwarded call to show the original number that called, so that if you miss the call you can call it back.

A calls B. B has forward to C, I want the A number to be shown on C after being forwarded from B.

I've heard this called caller "diversion", and that this has to be done with the providers.

Does anyone have any experience with this, and how they had to configure on OfficeServ to make this work?

What kind of trunks are you using?

Excellent question. This will definitely not work for POTS lines on any system.

The trunks are BRI, CO Lines, in P-P DDI mode. We're using a set of DID numbers.

I was able to figure this out after a lot of troubleshooting and testing.
In my situation, the only way to make this work is to use the MOBEX functionality with the help of a service provider technician.
I setup MOBEX stations with defined mobile numbers as the incoming/outgoing number, and then provided the external numbers to technician so he could add them to a "whitelist". The users that wanted the original CID to be shown on a forwarded call, would need to activate call forwarding on their office phones, to their defined MOBEX station that was setup with their external mobile number.

The technician was able to make a script/program on their side, that would compare the incoming call and the outgoing call that was made because of activated call forward to a MOBEX station,
and depending on that the original CID was "injected" into the outgoing forwarded call. Only with MOBEX does the correct number get sent out so the program worked so a normal call forward to a external number did not work.
Also this will not work on a MCP card, I was only able to get it working after switching to a MP20 card.