Not sure which route to take on an unlocked 5S - ATT or T-Mobile? Obviously, Sprint is out of the question. Will Apple begin to sell unlocked iPhones that are not exclusive to a specific network within a few weeks? I've read that T-Mobile requires 40 days of service before it can be unlocked. What if you purchase a full-price ATT 5S through the Apple Store, is it unlocked and good for use on T-Mobile's network? Thanks.