A T-Mobile spokesperson said to 9 to 5 Mac that most of the iPhones on the company’s network pre-date the iPhone 4, and now T-Mobile has more than one million iPhone running on T-MO 2.5 Network.
The company is working on adding Micro SIM cards as an option for customers, although a release date hasn’t been announced. Currently, T-Mobile offers only standard-size SIM cards which are substantially larger than the Micro SIM cards used in the iPhone and iPads.
T-Mobile will now get more iPhone running on its network after Apple started selling unlocked iPhones in the USA. However, they are taking advantage of T-Mo 3G or 4G bands.