T-Mobile’s faster 42 mbps network rolls out in 56 markets today. (JIN LEE/BLOOMBERG)

The enhancement theoretically doubles the speed of T-Mobile’s HSPA+ network, though the company has very few devices that are optimized for the network.

The company’s Rocket 3.0 plug-in laptop stick is designed to work on the faster network, as is an as-yet-unnamed smartphone due out this year.

That said, the company does promise that customers will see a boost in their network performance and reliability.

“No one ever stares at their mobile phone wishing the Web site would load slower,” said Chris Hillabrant, vice president and general manager, Mid-Atlantic, T-Mobile USA in a statement. “With that in mind, we’re giving our loyal customers in Baltimore and Washington D.C. our fastest, most reliable network, allowing them to browse the Web, download applications and stream content faster than before.”

Other major areas getting access to the faster network today include Boston, Charlotte, Indianapolis and Minneapolis- St. Paul.

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