Route Incoming to Different Trunk

I have the following configured, using trixbox and asterisk as indicated. both are current versions.

All works fine. Trixbox A can dial 3XX extensions, and outbound via Provider. Asterisk B box can dial extensions 2XX and dial outbound via Provider over 2 hops. The only question I have is: how can I route incoming calls on trixbox A with a particular DID directly to Asterisk B? Put another way, is it possible to have an incoming route whos destination is a trunk?

Thanks in advance.

+-----------+
| Provider  |
|           |
+-----------+
      ^
      |
     IAX
      |
      V
+-----------+
| Trixbox A |
|    2XX    |
+-----------+
      ^
      |
     IAX
      |
      V
+------------+
| Asterisk B |
|    3XX     |
+------------+