T-Mobile USA have upgraded their interactive coverage map showing the improvements to coverage following the roll out of their 700 MHz and 1,900 MHz 4G LTE coverage, boosting their 1,700 MHz and 2,100 MHz coverage. A number of users across at HowardForums are reporting the changes reflect the improvements made to T-Mobile's network, although one criticism I would level at the site is that it's difficult to distinguish between so many shades of magenta! Still, if you have pink at your Zip code, you should have T-Mobile US LTE coverage. However, if you already had solid T-Mobile coverage, you're unlikely to see much difference in the reported coverage.
Coverage maps may be used by networks to ensure that customers have coverage at their chosen home and work locations, but in the case of a modern carrier with LTE spectrum across a number of different frequencies it may be used to help customers pick the best device for their purposes. The T-Mobile US website for one stage further by providing useful information to help customers show devices compatible with their new 700 MHz and 1,900 MHz frequencies. This differentiation between LTE frequencies is important because the lower the frequency, the further the signal may penetrate into buildings but the slower the maximum potential network speeds obtained. As such, many carriers are using the low frequency spectrum to provide wide area coverage and installing mid and high frequency coverage to boost network capacity in busy areas. One of T-Mobile's network weaknesses is associated with their lack of low frequency coverage but they have been working hard on improving this.
It's great to see T-Mobile USA keeping the tools that help customers determine if they'll have coverage as up to date as they can along with their network improvements. The mapping data is computer generated and is not set in stone, but it's useful to giving an idea of coverage or for comparing carriers. Why not check your city using the source link below and let us know if you're seeing an improvement compared to the last time you checked it out? Going forward, the deal with Google to provide coverage for Big G's wireless service is likely highlight any areas of poorer coverage. I expect Google to be encouraging T-Mobile to shore up any and all weaknesses as they're discovered.