cricket help

[bakenast]

i decided to switch to cricket so i bought a galaxy s3 off ebay, it shows cdma, but it requires a sim from cricket to be activated, I was thinking cdma phones dont use sim cards but this one has a slot in the back, how can I tell which service towers it will use?

[rich hathaway]

that all depends on if you leave it set to ruim or u change it to nv only and flash it