The company is mostly built on Android devices, but has always tried to support the iPhone. The trouble was that until now, users had to cut down the existing Solavei SIM or microSIM cards to work in the iPhone 5, which can be a trick process. Now, the company officially offers nano SIM cards for iPhone 5 users.
Of course, iPhone users still need to be careful, because T-Mobile is still rolling out the 1900MHx spectrum, so the iPhone still doesn't get 3G speeds on the entire T-Mobile network. It works well in many major metropolitan areas, but still not all.