T-Mobile's iPhone Is Unique Variant of AT&T's Model
NOT quite Unique!
http://www.anandtech.com/show/6860/apple-to-ship-upd ... »
But yes, you must buy a new t-mobile iphone 5 to get the AWS HSPA+ support. I'd bet at&t pushed against a firmware update on existing iphones.
- Re: NOT quite Unique! by freek1989