No, you won't be able to use your phone in Key West. Unfortunately due to the proximity to the island of Cuba all cellphone coverage in Key West is provided by the Cuban Government. Because of the embargo it is illegal for you to conduct any financial transactions with the Cuban government. It is impossible for ordinary tourists to pay the Cuban Government for their services without breaking the monetary transaction rule. (Although you can work around this by buying counterfeit Cuban cellphones from shady street vendors.) Beware that you will not be able to bring the Cuban cellphone back into the continental U.S. (just throw it overboard when you are done with it). Also, if you attempt to place a call while in Key West with your U.S. cellphone it will be confiscated by U.S. authorities and returned to you at the end of your trip. *Please allow 2-3 weeks for delivery.