Prabath,
Is this a standalone Unity or a failover setup? This type of configuration would be accomplished on the CUCM. If it's a single Unity server, you could possibly stick the DN(s) that you want to be called at the very end of the line group that Unity's ports are in. If it's failover, you'd want to do the same, but put the DN(s) at the end of the secondary's line group since the second line group is automatically jumped to when the primary line group does not respond (if configured per the guide).
This is probably just one of a few different ways you could accomplish something like that. If anyone else has any input/ideas, feel free to interject.
Hope this helps. If so, please rate.
Brad
