Issue with extensions and no inbound rules

[c.holloway]

Good afternoon. We've run into something as we're migrating a client from CUCM to a 3CX environment. We have an Adtran 924 running as an SBC, this handles the PRI calling and sends the calls in to 3CX or Call Manager as needed as we transition. The CUCM server and 3CX are trunked together so userse on each system can communicate

What we experience is that even though a call from CUCM shows up at 3CX with the 4 digit extension pver the trunk, the call never rings properly until an inbound rule is also created that matches that 4 digit extension and routes it to the extension in 3cx.

I guess my question is, is this normal behavior? If a SIP call shows up at the PBX with a host part matching an extension on the system, why is an inbound rule also required?

 

[leejor]

What type of trunk(s) are you using? I would think that using a Bridge trunk, would route the call to an extension, but, if it is a "generic" type SIP trunk, then you'll probably need rules. The 3CX Activity logs should be of help in determining why the calls fail.

 

[NetVu IT]

Yes it's normal behaviour and something I've seen in both V14 and V15 with trunking. The only time the incoming rules don't appear to be needed is for 3CX to 3CX bridges. I don't know why it's required; I'd have thought it relatively simple to allow an extension match based on an incoming number mask.

 

[leejor]

I don't know why it's required; I'd have thought it relatively simple to allow an extension match based on an incoming number mask.

It's required because you don't want incoming calls routing off to a destination that you have not specified. With Bridge trunks, it is assumed that the other end is also a PBX, that you have control of the digits (format) being sent, so incoming digits are handled in the same manner as digits dialled by an extension.