At long last, T-Mobile will be carrying the Apple iPhone starting on April 12th. The fourth place carrier announced the news during a press event in New York on Tuesday. T-Mobile, the fourth largest carrier in the US, is the last national carrier to offer the iPhone, following behind AT&T, Verizon Wireless, and Sprint. The iPhone 5 will be compatible with T-Mobile's new LTE network, which was also officially launched on Tuesday, and will also feature HD voice. The carrier is also selling the iPhone 4S and iPhone 4 in "select markets"; naturally, the older models will only not run on T-Mobile's LTE network. The iPhone 5, however, will run on LTE, T-Mobile's "4G" HSPA+ network, and older GSM / EDGE networks — it sounds like T-Mobile's iPhone 5 either has slightly different radios than the current GSM version to enable full compatibility with its HSPA+ network or had these new bands enabled through a software update.

As part of T-Mobile's new Uncarrier branding and initiative, it will be selling the iPhone 5 slightly differently than its competitors. Instead of pressing customers to sign a two-year agreement, T-Mobile will let iPhone buyers either pay full price for the device at the time of purchase, or spread the cost over 24 months with installment plans. A 16GB iPhone 5 will sell for $99 up front with 24 months of $20 payments — that's $579 over the two years, $70 less than buying an unlocked iPhone 5 from Apple. Similarly, the iPhone 4S will cost $69.99 down plus $20 per month and the iPhone 4 will cost $14.99 plus a $15 monthly charge. Unfortunately, there's no word yet on what happens if you cancel your plan or want to buy a new phone before those 24 months are up.

T-Mobile has long supported unlocked iPhones on its network — it's even recently updated its network in many areas to better support the frequencies used by the iPhone and has been selling iPhone 5-compatible nano-SIM cards since this past October. But now that it is selling the device in its stores and online, T-Mobile won't need to be as aggressive in courting AT&T iPhone users to bring their phones over to its network. The question remains now, since offering the iPhone is no longer the advantage over other carriers that it was in past years, will carriers finally have to compete on pricing and network quality instead of exclusives on popular devices? We sure hope so.