T-Mobile officially announced that it would be selling the iPhone 5 as well as the 4S and 4 models on Tuesday. Lots of people wondered, though, to what degree Apple tailored the iPhone 5's hardware for the carrier, or if they could use their existing iPhones on T-Mobile's network. Well, according to an Apple representative who spoke to Engadget, T-Mobile's iPhone 5 will be a tweaked version of the A1428 model, which AT&T currently uses.

That tweaked version includes support for T-Mobile's Advanced Wireless Services-based network (AWS). But AT&T customers can't just hop networks: “Sadly, Apple affirmed to us that it's not something that can be enabled via a simple software update for A1428 iPhone units already in circulation.” Engadget reported. “To say that another way, existing iPhone 5 owners on AT&T cannot simply apply a software patch to have AWS support added. You'll need to buy a new phone next month.”

Still, the phones that will go to market on April 12 will be sold unlocked, so users could conceivably hop between the two American carriers (and other global carriers) as much as they like after they've purchased that new phone. Apple will sell the modified A1428 iPhone 5 for full retail price starting April 12 as well.

MacRumors added: “Apple plans to phase out the existing A1428 hardware in favor of the new version, which means future phones from AT&T might also ship with AWS support included.”