Call forward in custom context problem

I have several dept and each has a did and a group of ext. I have created a custom context for each so they dial out on their own pstn and the called ID will be correct.
All works as I expected but the the manager wanted to forward his ext to his cell so he used call forwarding *72.

Then when a call came into the ext it was forwarded BUT it used the first available trunk line NOT the one assigned to the context for that ext.
thus the caller ID was wrong ( pstn provider wont allow me to change it. :frowning: )
Any ideas how I can get this to work and use the proper trunk to call out?

using freepbx and asterisk and custom_context 0.3.7
the same on and asterisk and 2.8.0rc1.1


This is one of the limitations of the custom context module.

I would setup an outbound route for just his cell number that selects the right trunk.