In the United States, Android overtook Research In Motion's BlackBerry and led the smartphone OS market with a 34.1 percent share. By contrast, Android held a mere 3.9 percent share in the same period last year, noted Gartner Research Vice President Carolina Milanesi. "We are expecting Android to become the second-largest OS at a worldwide level before the end of the year," Milanesi said.

Apple's Sustained Momentum

Sales of Apple's iPad, which enjoyed successful international launches during the quarter, had no impact on the smartphone market, Milanesi noted. "We believe that most tablet users still feel the need for a truly pocketable, yet highly capable, device for those situations when it's inconvenient to carry a device with a larger form factor," she explained.

New smartphones from Apple, HTC and Motorola helped drive strong sales in the quarter. However, shortages of active-matrix organic LED (AMOLED) displays and other crucial components impaired sales of some of the more popular new smartphones, the research firm observed.

Apple's mobile-device sales reached 8.7 million and accounted for 14.2 percent of the smartphone market in the quarter. Gartner analysts noted that Apple's sales would have been even higher if it had not been forced to tightly manage inventory in advance of the iPhone 4's launch.

Furthermore, Gartner said Apple's sales suffered from some iPhone 4 supply constraints. The research firm expects a wider global rollout of iPhone 4 will sustain Apple's sales momentum throughout the second half of 2010.

Given that the iPhone 4's antenna problems didn't come to light until after the end of the second quarter, the news had no impact on Apple's latest results. Moreover, Gartner believes that the impact on sales will be very limited even in the quarters to come.

"Reception issues are more prominent in the U.S. than in other markets due to the network congestion you see," Milanesi said. "Apple stated that return rates on iPhone 4 are very limited."

Lower Cell-Phone ASPs

BlackBerry sales reached 11.2 million worldwide in the second quarter. And Gartner expects RIM to further benefit from the launch of devices running the new BlackBerry OS during the quarter currently under way.

"We believe the Torch's form factor will still appeal more to business users than to consumers and will stop many loyal BlackBerry users defecting to other platforms," the research firm's analysts said. "But it won't attract many new users to the brand."

Smartphones accounted for 19 percent of the global cell-phone market overall, which rose 13.8 percent to 325.6 million in comparison with the same period in 2009. Still, the double-digit growth wasn't entirely good news for handset makers, since average selling prices were lower than expected and margins fell, Milanesi observed.

"We attribute the decline in ASPs to a stronger dollar, a depreciating euro, and intense competition that drove price adjustments and changes to the product mix," Milanesi said.

Nokia retained its leading position in the global cell-phone market by shipping 111.5 million units, but the handset maker's global market share fell 2.6 percentage points from the year-earlier period to 34.2 percent. Samsung placed second with a 20.1 percent global market share.