I need some expertise to clear this up for me. I know eBay unlocks generally work for activated AT&T iPhone 5s, but I want to buy an AT&T phone from someone and then unlock it with an IMEI unlock on eBay. If I buy a shrinkwrapped, never activated AT&T-locked phone, do I have to first activate with AT&T (and whatever charges that incurs) before I can unlock it? What about if I buy a secondhand iPhone 5, that someone has already activated on their plan, but has since decided to sell? Do I have to activate or will an unlock free me from AT&T?