On-Net Calls to Cisco CUCM

[LeighHarrison]

Hello all,

We've got a 3CX system that we host for a customer and want to be able to make calls to their existing Cisco CUCM system. We've put a Generic SIP Trunk between the two and and make calls. We did trip up on having new DID's from the incoming trunk and mapping them to the relevant extensions and seem to have hit a bit of a snag, but I'm not sure if it's expected behavior.

Snag is: We dial a 4 digit number of an extension on the CUCM on 3CX and the call runs through, but shows the full DID number of the 3CX phone, rather than the 4 digits of the 3CX phone. I've changed the Outgoing DID from the full number to the 4 digit extension number (in this case 7601), and that then sends correctly, but breaks the outgoing main SIP trunk to the PSTN.

Is there a way I can keep 4 digit dialing and call display between the 3CX and CUCM, and also have the full Outgoing DID for the main SIP trunk to PSTN?

I've tried a few settings on the Trunk specifically, under Options->Caller ID Control, with From, Remote Party IS and P-Asserted Identity all set to ""LineID" internal number of line", but get the same results.

Can someone point me in the right direction?

Best, Leigh

 

[leejor]

Even though it is not officially supported, you might want to try using a Bridge trunk instead, as calls over that are considered internal. You could set one up in parallel to the existing trunk for testing.
I know that in the past that even when using a Bridge trunk to a CUCM, there can be caller ID issues, but, as I recall, usually more to do with placing outside calls though the other PBX.