First and foremost, sprint does not use sim cards!! Second, You can't use a RAZR on sprint. Why dont you get the samsung mm a900, it's the closest thing to the RAZR !!! Spelled like that.
I was planing on buying a Razar and using it on the Sprint network, after reading a bit i wanted to know is this possiable (using a RAZAR on a Sprint network), and do I have to Buy a Sprint Sim Card?