ComScore (, a company that measures the digital world, today released data from the comScore MobiLens service, reporting key trends in the U.S. mobile phone industry during the three month average period ending in September.

The report ranked the leading mobile original equipment manufacturers (OEMs) and smartphone operating system (OS) platforms in the U.S. according to their share of current mobile subscribers ages 13 and older, and reviewed the most popular activities and content accessed via the subscriber’s primary mobile phone. The September report found Samsung to be the top handset manufacturer overall with 23.5% market share, while RIM led among smartphone platforms with 37.3% market share.

For the three month average period ending in September, 234 million Americans ages 13 and older used mobile devices. Device manufacturer Samsung ranked as the top OEM with 23.5% of U.S. mobile subscribers, up 0.7 percentage points from the three month period ending in June. LG ranked second with 21.1% share, followed by Motorola (18.4 % share), RIM (9.3% share, up 0.5 percentage points) and Nokia (7.4% share).

Approximately 58.7 million people in the U.S. owned smartphones during the three months ending in September, up 15% from the preceding three month period. RIM was the leading mobile smartphone platform in the U.S. with 37.3%t share of U.S. smartphone subscribers, followed by Apple with 24.3% share.

ComScore says Google continues to gain ground in the market, rising 6.5 percentage points to capture 21.4% of smartphone subscribers. Microsoft accounted for 10% of smartphone subscribers, while Palm rounded out the top five with 4.2%. Despite losing share to Google Android, most smartphone platforms continue to gain subscribers as the smartphone market overall continues to grow.