Make CNAM lookup also work internal trunks

Using Opencnam.
As I understand it, CNAM lookup works on inbound routes.
Is it possible to make lookups happen also on internal SIP trunks without inbound routes?

We have most of our calls come in on a Digium PRI gateway, which connects to our FreePBX server via a SIP trunk, with no inbound routes.

Anybody who can help?

This is the part where I just don’t know how to help. Is there any way that you can include even an “any/any” inbound route that you can use?