Resolution:
This configuration is sometimes referred to as a "directory gatekeeper". The MXM 3.1 release added the ability for the MXM to be configured as a "child" to a "parent" or "directory" gatekeeper, and the MXM 4.0 release is able to be either a "child" or a "parent/directory".

1. On the MXM administration console, add a new zone from either the "Nodes" menu or via the smart icon for adding a zone.
   
   
2. Make sure the zone prefix of this new neighbor zone matches the dial plan schema you have established.
   
   
3. On the properties tab labeled "Zone Settings" you will see preference settings for the relationship to this new zone: Neighbor, Parent Directory Gatekeeper, etc.

If the MXM is configured in a hierarchy with RADVision ECS gatekeepers, there are some specific recommendations for the ECS configuration. These recommendations are described in another VCON support note.