We will be traveling in Costa Rica soon. Will our iPhone's work? What are the rates? Is there anything we need to do so that the phones will work? What about the data? How do we call a phone in Costa Rica while we are in Costa Rica using our US iPhones? How do we dial a U.S. phone while in Costa Rica. What are the data charges? Any input would be greatly appreciated. Any further tips you can add that I may not have thought to ask would be greatly welcomed. Thank you.