Earlier this year, T-Mobile spent nearly $8 billion on buying 31MHz of 600MHz low-frequency spectrum, also known as Band 71, that was part of an FCC auction. Due to low frequency, users will have better signal, but there is only one handset that currently supports the Band 71 and that is the LG V30.
However, that will soon change as the FCC documents reveal that Samsung is about to release a phone that works with the 600MHz spectrum. A new version of the Samsung Galaxy S8 Active (SM-G892U) has been certified by the FCC and is compatible with both Band 66 and 71. There is also an unlocked model coming to the US by the end of the year.