As U.S. cell phone shipments continue to fall, the U.S. smartphone market appears to be consolidating, according to a report from Strategy Analytics, which said Research-In-Motion's BlackBerry continues to dominate the business market.

In separate reports, the market research firm found that handset vendors shipped just 245 million cell phones worldwide -- down 13% from 282 million handsets shipped a year earlier -- but in the United States, RIM held 37% of the U.S. business market, followed by Microsoft Windows Mobile platform, which captured the second-place position with 26%.

"This research shows that the U.S. market is consolidating, with many companies working primarily with AT&T, Verizon, and, to a lesser extent, Sprint Nextel," Strategy Analytics' Andrew Brown said in a statement. "What also emerges is that RIM customers expressed a lower willingness to churn that those on other platforms." Brown is director of wireless enterprise strategies at the market research firm.

As for carriers in the business market, Brown found that AT&T appealed more in large enterprises while Verizon penetrated smaller companies with fewer than 100 employees more. The Strategy Analytics report also found that Apple's iPhone, Google's Android, and Nokia's Symbian were not serious contenders in the U.S. business market.

The smartphone market is generally growing and is paced by RIM, which shipped 7.8 million BlackBerry handsets in the three months ended Feb. 28. As for the iPhone, whose providers at Apple have aspirations of cracking the business market, Strategy Analytics said 3.8 million iPhones where shipped in the first quarter.

Another Strategy Analytics analyst, Neil Mawston, noted that the poor worldwide economic situation amplified the negative first-quarter numbers, which, coming after the traditionally robust holiday selling season, were impacted by retailers destocking inventory. The decline in shipments led to employment layoffs at Motorola, Nokia, and Sony Ericsson.

Earlier this week, IDC reported that cell phone shipments had dropped nearly 16% in the first quarter.

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