According to Apple's web page listing LTE bands by model, the T Mobile versions (A1687 & A1688) lack band 30 while the AT&T versions (A1633 & A1634) have band 30. Otherwise they appear to be the same. I purchased the AT&T version at full price through Apple. When I received it I connected to iTunes upon unboxing to do a new setup and update to 9.0.1 so I could restore from my iP6 backup and when I did I received the "Congratulations you're unlocked" screen. Wasn't expecting that and figured I'd have to request it through AT&T but got it straight away.