I just restored and upgraded my iPhone to 8.0. I originally restored it on 7.0 so that i could get it unlocked by AT&T. When i restored and upgraded to 8.0 without the SIM card in, it said couldn't activate phone. So i put the old sim card in there and then it said phone is now unlocked. So what I'm asking is. do i have to keep my sim in the iPhone 5 to unlock it and then just take it out? I don't want to sell my phone with personal info, but i want to make sure it is carrier unlocked.