Dialing external extensions from IVR

I have two asterisk boxes talking to each other via an IAX trunk, that all works fine. Phones from one box can call phones on the other box no problems. My question is when a person dials into Box A and trys to reach an extension on the other box it says they have dialed an invalid extension.

My outbound IAX trunk is names IAX_Out and I have tried using the following line in my IVR but it gives the same response. Any help would appreciated.

exten => _2XX,5,Dial(IAX2/IAX_Out-peer/202)

BTW Box A uses 1XX extensions and Box B uses 2XX

it looks for me like operating in diffrent contexts
Box A users are in context [BoxA] and can dial to BoxB
but contexts handling incoming calls to BoxA don’t have permission to
make a Dial to BoxB