sprint phones don't use sim cards. they use what is called CDML technology. so when you get the phone, they have to punch a bunch of numbers into the phone to program it. the only companies in the US that use sim cards are AT&T and T-Mobile. all the rest use CDML. bad thing about it is the US is behind in technology in cell phones because most carriers still use CDML, and all the other countries in the world use GSM (sim cards)