The Sony Xperia Z (C660X) may be getting closer to a launch on T-Mobile US as firmware has been certified by the PTCRB website for the C6606/C6616 variant. We expect that this model(s) will have the necessary LTE support for North America.
The C6606 SKU would most likely support LTE bands 1, 2, 4, 5 and 17. We don’t know whether the C6616 model is a different model altogether, however given the single listing on PTCRB, there may be a slight tweak to the frequency band support. Hopefully, we’ll hear some concrete news on a T-Mobile release soon.