Transferring Phone Book

I am trying to transfer the phonebook from my Palm Centro to the Prius. I am able to perform the transfer, and all of the names show up as expected. The problem is that *most* of the phone numbers end up in the Prius phonebook as "+1". There are a few numbers that make it through intact, but I can't determine what is special about those entries that allows the entire phone number to come across.

Has anyone run into this before? Any ideas whould be appreciated.

Allen