So my local Best Buy is selling two open box A&T white 16GB iPhones right now for $490.00. Was told both were returned in just a few days. I want to put them on Straight Talk or Net 10 for myself and my wife. My question is, do they have to be unlocked, or will they work locked if I just switch out the sim? They also have a 4S for $400, that I thought might be easier to pick up, since it doesn't have a nano sim, although Net 10 does sell them. Straight Talk requires you to get a cutter. Wanting to know what I'm getting to exactly. If I have to get them unlocked, any recommendations on EBAY before the listings go away?