Force Treo to always dial a country code by default?

I recently picked up a Treo Pro last month, and have been getting used to it. Apart from the keyboard (it's a little hard to type on), it's a great phone, but there's something I'm really missing.

I do a lot of international travel (the mobile bills my company gets must be staggering some months), and many of the US numbers I have stored in Outlook lack the "+1" country code. On my old 680, there was an option to have the phone dial a +1 for any number in the contacts list which didn't have a country code prepended. That means that dialing US numbers while overseas can be a chore if the +1 isn't already added.

After scouring Google, I can't seem to find any such option in Windows Mobile. Anyone have an idea about how to force WinMo to do this?

Settings > Personal tab > Phone > Services tab > Automatic Prepend > Get Settings button

But it should already be set to automatically add 1