Yes, you can use CaptionMate to call phone numbers outside of the United States. To make an international call, first dial "+" on the keypad (the U.S. exit code), followed by the country code and the phone number. To add "+," please firmly press "0" until "+" is added automatically at the top of the keypad screen.
For example, to call a phone number in Germany, open the CaptionMate keypad, dial "+49" and then dial the local phone number.