Does anyone know if there's a Hardware difference between the iPhone 4S Models: T-Mobile's vs AT&T's??? Currently, I'm using an AT&T Factory Unlocked with T-Mo's Carrier Update. Although, I need to depend on the 3G/4G 1900MHz refarmed signal to get real 4G. I heard, from T-Mo Rep that a T-Mo iPhone 4S (or iPhone 5, of course), DON'T depend on the refarmed frequencies. Can anyone confirm iPhone 4S Models: T-Mobile's vs AT&T's hardware?????