Calls forwarded to external numbers always use primary Trunk number

[uknotbot]

For some reason this appears to be the only forum I can post in - so apologies.

I am currently using Professional Annual 4SC self hosted, using Gradwell SIP Trunk. Gradwell is a preferred supplier.

My Problem:
Any call that gets forwarded to an external number (such as user diverting on "Do Not Disturb" to a mobile) - sends the primary trunk DID rather than their own DID for their extension or the originating callers ID.

Any calls to my Ring Group - also sends the Primary Trunk number rather than forwarding the OriginatingcallersID.

Steps I've taken so far:

https://www.3cx.com/community/threads/cannot-set-caller-id-on-v20.129156/#post-615391

1. The highest priority is the "Outbound Caller ID" field that can be set in the Outbound Rules.
   
   This is currently empty
2. If that is empty, then the Outbound Caller ID is taken from the Extension settings.
   
   Every user has an assigned DID number and their Outbound Caller ID number matches their Assigned DID number
   
   
3. If this field is empty, then 3CX will check the SIP Trunk settings → “Options” tab → “Caller ID Control” → “Default Outbound Caller ID” field.
   
   Default Outbound Caller ID is blank
   From : Display Name -- OutboundCallerID
   Remote Party ID - Calling Party : Display Name -- OutboundCallerID
   P-Asserted Identity : Display Name -- Default
   
   I've experimented with a number of different things here but all seem to have the same results. If I populate the default Outbound Caller ID with a DID number then all calls use that so I reset it to blank. Even with the settings as above, all extensions make external calls using their correct DID - but calls external calls forwarded by them use the default trunk DID.
4. If this field is also empty, 3CX will use the Main Trunk Number configured in the “General” tab of the SIP Trunk settings.
   
   This is the number that is being used for forwarded calls.

Any help would be gratefully received!

 

[SteveITS]

Per https://www.3cx.com/partners/sip-trunks/uk/ they don’t support clip no screening so I don’t think it’s going to work.