T-Mobile has already started to use their newly-assigned 600 MHz spectrum:
"BELLEVUE, Wash.-- Damn that was fast.
T-Mobile today announced it has begun lighting up its new
600 MHz LTE network — leveraging the
massive haul of super-premium low-band spectrum won in the government broadcast incentive auction concluded earlier this year. The announcement comes only two months after the Un-carrier received its
spectrum licenses from the FCC. T-Mobile’s first 600 MHz LTE network sites — the very first in the world — were just switched on in Cheyenne, Wyoming using Nokia equipment. Starting in rural America and other markets where the spectrum is clear of broadcasting today, T-Mobile plans to deploy the new super-spectrum at record-shattering pace — compressing what would normally be a two-year process from auction to consumer availability into a short six months.
"T-Mobile today also shared additional details of its 600 MHz LTE network rollout. This year alone, additional 600 MHz sites are slated for locations including Wyoming, Northwest Oregon, West Texas, Southwest Kansas, the Oklahoma panhandle, Western North Dakota, Maine, Coastal North Carolina, Central Pennsylvania, Central Virginia and Eastern Washington. Those deployments and other network upgrades will help the Un-carrier increase total LTE coverage from 315 million Americans today to 321 million by year’s end."
What's the catch? There are no 600 MHz-capable handsets available...yet. There will be, probably by the end of the year. This is indeed an aggressive expansion and could be a game changer within a very short time.