Wanted to let everyone know that some Sprint phones are now supporting
SIM cards. I actually have a Samsung Ace on the Sprint network, and if I open the back battery compartment, just above the battery, there is the
SIM card. You have to remove the battery to get the
SIM card out, but it's there and it's completely usable on the Sprint Network. Not sure if all of their phones use them now, but I know that the Ace does. Hope it helps.