According to the asterisk config extensions.conf information page on voip-info.org (http://www.voip-info.org/wiki/view/Asterisk+config+extensions.conf), it should be possible to use something like:
exten => 123/100,1, …
This matches a dialed number of 123 if the caller id is 100.
Should this syntax work in FreePBX for the Dial Patterns entry for outgoing routes? I was hoping that this would allow me to easily limit outgoing routes to one extension without having to manually hack the configuration files.