I have a T-Mobile contract, and intend to jailbreak and unlock the iPhone 4 when a jailbreak comes out, which shouldn't be far away. Now since you still need to have AT&T to buy a no commitment iPhone, and I dont, if I walk into a Best Buy with my friend (who has AT&T), can I buy a no commitment iPhone through his AT&T account? Would there be any additional charges on his side or no?