I'm sure they will catch some slack for their new 'Uncarrier' prices, but that's beside the point. According to new reports, it might not be so easy for customers to bring their existing device over to T-Mo's shiny new 4G LTE network. That's a bummer, because I'm willing to bet that a lot of their business would be from parties trickling off their main carrier- moving away from contract-only service.
T-Mobile is building a new 4G LTE network, that's for sure. They are restructuring the existing 3.5G data service from the AWS band (at 1700MHz) to a 1900MHz band service. At first glance it would seem like they making a move closer to AT&T's service frequencies, but that's actually not the case.
According to an Engadget report, even though the T-Mobile and AT&T iPhone 5 models are identical, AT&T's model is locked down which means no T-Mobile 4G LTE signal support through the AWS band. Long story short, you can't use an iPhone 5 from AT&T on T-Mo's 4G network.
Okay, so what, that just applies to the iPhone, right? Sorry Android brethren, it holds true for more than just Apple's devices it seems. For example, an unlocked version of the HTC One won't even work on T-Mobile's LTE network. Unless the device in question specifically supports LTE class 4 (AWS) frequencies, you will not be able to use the 4G speeds- instead, you'll be stuck on the standard 3G speeds. Luckily, T-Mobile says "most" unlocked phones with 4G LTE support in the AWS band will be compatible with their network.
That being said, you can still use T-Mobile's network for the most part if you don't have a compatible 4G device, you just won't be able to take advantage of the new speeds.
For now, the best option might be to pick up a device directly from T-Mobile. After all, how could you walk away from those amazing prices, especially when there are no contracts involved.
Hopefully you were able to detect my sarcasm at the end there.