Any chance you could add 406 number support for contacts when direct dialing? I know you can't get access to the numbers, but you can a person's 406 number when they text you.

Could you check for something like the following in the notes section for each contact?:
GV:406-201-5689

If that exists you could dial it instead, which would make outgoing dialing even faster (and not always require a data connection).