Unable to Override Trunk-Level Caller ID (Shared Trunk- Multi-Client 3CX Instance)

[AnonymousMD]

Hi Support!

We are currently facing an issue with outbound Caller ID behavior in a shared environment and are seeking clarification or guidance.


Scenario:
– Our 3CX instance hosts multiple clients (20+ clients) within a single installation.
– All clients share the same SIP trunk.
– The trunk-level Outbound Caller ID is statically set ex. "Company1" and cannot be removed or changed, as it is required for billing and tracking purposes across all clients.
– We are trying to configure per-extension outbound Caller IDs, so that each client can present their own identity when making outbound calls.

Steps we have taken so far:
– We set a custom Caller ID at the Extension level → Result: Outbound calls show as Anonymous.
– We set a custom Caller ID via an Outbound Rule → Result: Outbound calls show as Unknown.
– Despite both settings, the system defaults to the trunk-level Caller ID (Company1) on outbound calls.

Is there a supported way to configure per-extension outbound Caller IDs in this scenario, where a single trunk with a required trunk-level Caller ID is shared across multiple clients/extensions?

 

[YiannisH_3CX]

Hello @AnonymousMD

There are 4 places you can configure the Outbound Caller-ID to be used.
1. Outbound rule --> This overrides all other outbound caller ID given that the call uses this outbound rule to go out.
2. Extension Outbound Caller ID --> If the Outbound caller ID in outbound rule is empty then the extensions caller ID has priority
3. Trunks "Default Outbound Caller ID" in trunk Options tab --> When the previous 2 are empty this will be used.
4. Trunks main trunk number --> When everything else is empty the system will use the trunks main trunk number as outbound caller ID.

The above will work if of course the trunk is set up correctly. If you have static values in the template level then you cannot override them. Also before doing any changes populate the Outbound rule with a caller ID and attempt a call. Run a pcap and check if 3CX is sending the correct caller ID or not. If it does then speak with your provider. If it does not then export the template and check the configuration.

 

[AnonymousMD]

Thank you Yiannish. That answers our query.