Following years of speculation, the No. 4 domestic carrier has now officially launched Apple's (NASDAQ:AAPL) iPhone.

At T-Mobile's "Un-carrier" event today, the company announced that the iPhone will launch on its network April 12. T-Mobile also recently completed its shift away from smartphone subsidies and service contracts.

Instead, T-Mobile is offering a payment plan to make the device more affordable, with an upfront payment alongside 24 monthly payments for the iPhone. T-Mobile also said it launched 4G LTE service in seven major metropolitan markets, and plans to expand LTE coverage to more than 200 million people by the end of 2013.

T-Mobile has always welcomed unlocked iPhones on its network, although previously those devices were relegated to slower speeds due to technical incompatibilities.