T-Mobile Will Sell a Tweaked A1428 iPhone
The iPhone 5 that T-Mobile will be selling on April 12th will be a tweaked version of the A1428 iPhone (the iPhone that AT&T uses). T-Mobile needs to tweak the A1428 to work with the Advanced Wireless Services (AWS) bands.
According to an Apple representative that spoke to Engadget this morning at the T-Mobile event, the existing A1428 can’t be updated to support AWS.
Apple’s enabling support of the AWS bands from the factory on the new guy – and 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. 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.
On April 12th Apple will start selling the tweaked A1428, which will be unlocked and work with T-Mobile and AT&T. This means that AT&T might sell the tweaked A1428 as well.
The reason T-Mobile need the tweaked version is due to the speed of the phone. The original A1428 will work with T-Mobile, but it will not notably slower than the tweaked version.