Get the card before you go and the people at home will have your number. It does work the same way the France tim card works.The reloading of airtime was simple. Look for a tabac ,the cafes are small bakery/coffee places. You actual don't buy a new card but you give them your number and the amnount you want to add to the card 5,10,15 Euros . I got message from the card telling me if I reloaded the card I would get 20 Euros worth for 10. It was very easy

Where is a good place to buy one beforehand in US?