Im buying a used iphone from a guy at school for $40 cause the home button is broken. Other than that it works fine, I know that cause he let me use it for a little bit. Can I just put the SIM card from my samsung eternity into the iphone? or do I need to unlock it or anything? I know i'll need to jailbreak and get mquickdo or something to replace the home button. But my plan right now is unlimited texting not data. So if I disable 3G at home it wont cost anything to download apps right?