T-Mobile on Friday updated its support forums (via TmoNews) to detail the new features the carrier update will bring. All eligible iPhones using a T-Mobile SIM card will now have access to Visual Voicemail, the Commercial Mobile Alert System, and LTE connectivity on T-Mobile's AWS spectrum for iPhone 5 users.
The update also brings HD Voice to T-Mobile iPhone 5 users, and it contains device/network optimizations that will improve battery life.
The update is restricted to iPhones running iOS 6.1.x or higher. Rumors of the update leaked earlier this week, and it has rolled out as predicted.
T-Mobile's network currently hosts roughly two million iPhone customers using unlocked devices, adding about 100,000 more per month. The carrier will begin officially carrying Apple's smartphone on April 12, with a 16GB iPhone 5 available for $99. Pre-orders for the device began on Friday.