Many of you are probably aware of the fact that T-Mobile purchased a big chunk of 700MHz spectrum from Verizon back in January. Well T-Mobile is planning to have that rolled out by the end of this year. So, in theory, we should start seeing newer devices supporting band 12 LTE in the next few months. Since T-Mobile is going to want as many devices on that band as possible, seeing as it'll allow for better signal indoors, since it's a lower frequency. The Samsung Galaxy Tab 4 8.0 and Galaxy Avant which just launched, both support the 700MHz band already. And we had heard that the Sony Xperia Z3 would be supporting it as well. However, it looks like that has changed. According to TmoNews, "only supports band 12 on 704-716 / 734-746 MHz. This excludes the lower A-block spectrum" which means it would not be compatible with the 700MHz spectrum that T-Mobile has and will be rolling out this fall. Well that sucks, but then again we don't even know if T-Mobile is getting the Xperia Z3.
A writer for Extreme Tech, Neal, Posted about this whole thing ( @Det_Conan_Kudo):
This is going to suck for those that like to buy unlocked Sony devices and use them in the US. As it won't really work well on either T-Mobile or AT&T. So hopefully there is an US-based model that Sony will sell. Although we may be getting ahead of ourselves here as we haven't even been introduced to the device yet.