Canada's Research in Motion (RIM), makers of the popular Blackberry devices, was the leading mobile smartphone operating system in the U.S. in December 2009 with 41.6 percent share of U.S. smartphone devices according to a recent Comscore report.

Apple ranked second with a 25.3 percent share, followed by Microsoft with 18.0 percent share, Palm with 6.1 percent share, and Google with 5.2 percent share.

The facts and figures were contained in comScore's Mobilens report which reported key trends in the U.S. mobile phone industry over the three monthperiod between September and December 2009.

In addition to reporting on Smartphone users, the report found a total of 234 million people age 13 and older in the U.S. used mobile devices in December 2009. Device manufacturer Motorola was the top ranked OEM with 23.5 percent of U.S. mobile devices. LG ranked second with 21.9 percent share, followed by Samsung (21.2 percent share), Nokia (9.2 percent share) and RIM (7.0 percent share).

When asked about how they used their mobile phones in December, 63.1 percent of U.S. mobile subscribers used text messaging on their mobile device, up 2.1 percentage points from three months prior. Browsers were used by 27.5 percent of U.S. mobile subscribers (up 1.5 percentage points), while subscribers who played games made up 21.6 percent (up 0.2 percentage points).

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