T-Mobile isn’t saying where it’s launching LTE, so it’s a good thing we have OpenSignal to do our legwork for us. With its crowdsourced Android app, OS reports today that it has detected T-Mobile’s new LTE network in eight cities: Denver, Las Vegas, Kansas City, New Orleans, New York, San Diego, San Jose, and Seattle.

“The fact that our app has detected a T-Mobile LTE network in these cities suggests that they will be included in the initial LTE rollout,” OS spokesman Samuel Johnston said.

And while T-Mobile has only announced the BlackBerry Z10 and Samsung Galaxy Note II as LTE devices, OS says it’s also seen T-Mobile Samsung Galaxy S III and Galaxy S4 phones hitting the LTE network.

How fast is it? Johnston said OSM’s tests saw 25Mbps downloads, 8Mbps uploads, and latency around 40ms. That’s extremely fast for a 5×5 LTE network like T-Mobile is running.

“Obviously the network is under a very light load right now and these speeds will come down,” Johnston said.

T-Mobile is the last national carrier to launch LTE. It has pledged to cover 100 million people with LTE by midyear. Earlier this week the company treated us to a test of how the network will function after the upcoming MetroPCS merger, when it can double its spectrum in many markets to 10×10.

The carrier is having a network-themed press event on Tuesday, March 26 where it’s expected to announce a new range of service plans and more details about its LTE network.

Late last year, T-Mobile CEO John Legere said the company would be moving entirely to no-contract “value plans.” Tmonews has details of those new service plans(Opens in a new window), adding that traditional subsidized contracts will still be available from third-party retailers. 

The full OS report on T-Mobile LTE coverage is available at OpenSignal’s website(Opens in a new window). We’ll also be visiting all of the cities listed above in our Fastest Mobile Networks testing this May.