Bellevue, Wash. - T-Mobile is boldly going where other national carriers have gone just a day or two ago.

The carrier announced plans to launch its first BlackBerry smartphone using the new BlackBerry 7 OS and high-speed 1.2GHz processor.

Beginning Aug. 31, T-Mobile will begin selling the BlackBerry Bold 9900 at $299, after a $50 mail-in rebate and two-year service agreement with qualifying Classic voice and data plans, through T-Mobile retail stores and select dealers and national retailers nationwide.

For T-Mobile's business customers, the device became available today through an exclusive presale.

The 9900, equipped with a touchscreen and fixed QWERTY keyboard, will be T-Mobile's first 4G Bold and its first BlackBerry phone with the new BlackBerry 7 OS. The 9900 and another new BlackBerry 7 OS phone in RIM's Bold series are the thinnest BlackBerrys ever, at 0.41inches.

In recent days, Verizon and Sprint announced plans for the BlackBerry Bold 9930; Sprint announced the BlackBerry Torch 9850; and AT&T announced plans for the BlackBerry Torch 9810, Bold 9900 and Torch 9860. All phones use the new OS and 1.2GHz processor.