A screenshot of one of the more impressive speed tests of T-Mobile's wideband LTE.  T-Mobile has a product that is perhaps more impressive than any other in wireless right now. The Uncarrier is calling it "Wideband LTE" and it is by far the fastest wireless broadband connection available in the United States. 

While in Seattle at T-Mobile's splashy Uncarrier event at the Paramount Theater last week, I was shocked at the speeds I was getting on an iPhone 5S demo unit, which T-Mobile loaned journalists as a way of offering them a taste of its new "Test Drive" program. Even in the basement of the theater, I saw 88 Mbps download and 25 Mbps upload. I'll concede there might have been a COW in the area for that kind of in-building performance. 

Admittedly skeptical, I tried Speedtest again when I got back to my hotel room on the seventh floor near Safeco field. It was just before midnight and the results of that test were perhaps less sensational but still very good--31 Mbps download and around 1 Mbps upload. 

The next day, I left my hotel and tried Speedtest again on my way to the light rail station--76 Mbps download, and 28 Mbps upload. 

Those numbers are only possible via the kinds of wide swaths of contiguous spectrum upon which T-Mobile has the luxury of deploying its Wideband LTE product. Specifically, T-Mobile is deploying this offering on 15X15 MHz swaths of AWS spectrum. It's a luxury few other carriers have and could be one of the reasons T-Mobile has been less vocal recently about its need for more airwaves. 

This is T-Mobile's way into major metropolitan markets, where it will continue to take subscribers from the likes of AT&T and Verizon. Yes, Verizon has its XLTE product, and Sprint has its "Spark" offering, but neither of those can touch the kinds of speeds T-Mobile is putting up right now. 

Coverage is T-Mobile's weak spot but the carrier is being smart in not misleading potential customers with false claims. At the Seattle event, both CEO John Legere and CTO Neville Ray told those in attendance that T-Mobile's service may not be for everyone, particularly those who live in suburban or rural areas where coverage is spotty. Here in Madison, WI, I would probably not opt for T-Mobile. There is almost no retail presence in this city and even downtown there are dead zones or areas where the 5S falls back to an EDGE connection. 

It's for this reason that T-Mobile's new Test Drive promotion is such a great idea and fits perfectly with the company's strategy. This is a way to allow customers in large urban markets like Seattle, Portland and Orlando, to experience Wideband LTE. For now at least, the major metropolitan areas are where T-Mobile will continue to scoop up new customers and given the network performance in those markets, I'm guessing those customers won't be churning anytime soon. Providing a way for customers to preview the service serves to ensure they'll be sticking around.  

Last week's event in Seattle was previously scheduled for Los Angeles, but T-Mobile picked up stakes and booked the Paramount on news of Amazon's event happening on the same day. That Seattle, like Los Angeles, is a market where Wideband LTE could be demonstrated probably made the location change a no-brainer for T-Mobile. 

Wideband LTE is limited to certain markets and still hasn't made its way to places like San Francisco and Manhattan. Nevertheless, T-Mobile has currently deployed its Wideband LTE in: Atlanta, GA, Birmingham, AL, Columbus, OH, Dallas, TX, Detroit, MI, Honolulu, HI, Houston, TX, Jacksonville, FL, Los Angeles, CA, Minneapolis, MN, Mobile, AL, Orlando, FL, Portland, OR, Seattle, WA, Tampa, FL, and Upstate, NY.