Custom Context System Calling (callback) configuration

Ok so I have a bit of a issue with a FREEPBX server that I’m hoping someone can help me.

I have a server with multiple clients that use it. I use the custom contexts module to send the appropriate outbound calls out the correct customers trunks. (this all works fine)

One of my customers is a customer who just uses the service as a conferencing service for their branches. The issue is that as part of the conferencing service they have the ability to “call back”.

The issue being that the call back service is imitated by the server and has no way of being associated to a context or specific outbound trunk (Route).

Any ideas how I could do this???

Thanks in advance…