Guys, this time I got my hands on a 3GS. It's very cool My friend gave it to me for free as he's getting an iPhone 4. He told me he's going to take the SIM out of the 3GS and put it in his iPhone 4. So can I still unlock the 3GS without a SIM inserted? And before I unlock do I have to make any changes in Settings? Because I don't want to end up somehow "disabling" my friends SIM Card.