I found this information:
Disney Cruise Line is introducing wireless internet ship-wide on the Disney Magic as well as stateroom access for cell phones on May 12. (The Disney Wonder will have these enhancements later this summer.) Cell phone usage will be prohibited on the public decks, so I believe you'd have to make the call from your stateroom.
You'd need to check with your cell phone provider for rates and required access for international service.
Tammi, Team INTERCOT Moderator
Disney Cruise Line & Accomodations
Please visit our Sponsors