T-Mobile today announced it is doubling the speed of its 4G network in more than 50 markets to achieve theoretical peak download speeds of up to 42 megabits per second (Mbps). T-Mobile customers in 55 markets will now have access to increased 4G network speed, capacity and reliability. These markets include Atlanta, Ga.; Chicago, Ill.; Denver, Colo.; Detroit, Mich.; Dallas and Houston, Texas; Los Angeles, Calif.; Miami, Fla.; New Orleans, La.; Phoenix, Ariz.; Pittsburgh, Pa.; Portland, Ore.; and San Francisco, Calif., among others.

In addition, T-Mobile’s first 42 Mbps-capable 4G product, the T-Mobile Rocket 3.0 laptop stick, will be available for purchase beginning tomorrow, May 25. The Rocket 3.0 will be available at select T-Mobile retail stores and online at www.T-Mobile.com tomorrow for $99.99 after a $50 mail in rebate, with a qualifying mobile broadband plan on a two-year service agreement.

T-Mobile claims its current HSPA+ (4G) network runs at 21Mbps, but it hardly reaches 5-7Mbps in real world tests. How far this 42Mbps claim will go? Maybe 10-14Mbps in real world network speed, which is good compared to AT&T’s HSPA+ network speeds. However, these download speeds are nowhere near to what a real 4G (LTE) network can offer.