Apple emerged as the best-selling handset OEM in the fourth quarter of 2011, according to NPD Group. Apple accounted for 43 percent of the U.S. smartphone market during the quarter, which was helped along by new carrier partners Sprint and C-Spire, as well as the holiday push and the iPhone 4S.

Ross Rubin, executive director of connected intelligence for NPD Group, said consumers attracted by a faster processor, improved camera and the Siri speech-driven agent were willing to pay a premium for the iPhone 4S, making it the top-selling handset in the fourth quarter.

"The iPhone 4S outsold the iPhone 4 by 75 percent, and outsold the iPhone 3GS, available for free on AT&T, five to one," Rubin said.

Operating System Share ...The iPhone 4S was the top-selling smartphone, followed by the iPhone 4, iPhone 3GS, Samsung Galaxy S II and Samsung Galaxy S 4G.

Android stood out as the top smartphone pick for those new to the market. Among the first-time smartphone buyers in the quarter, 57 percent purchased Android phones compared to just 34 percent who purchased iPhones.

Android and iPhone accounted for over 90 percent of smartphone sales overall, with Android holding on to 48 percent of the smartphone market during the quarter.

"Android has been criticized for offering a more complex user experience than its competitors, but the company's wide carrier support and large app selection is appealing to new smartphone customers," Rubin said. "Android's support of LTE at Verizon has also made it the exclusive choice for customers who want to take advantage of that carrier's fastest network."

The overall share of mobile phone sales that are smartphones continued to climb in the fourth quarter, reaching 68 percent of the total mobile phone market, which is an increase of 18 percentage points since the year-ago quarter. Average selling prices (ASP) for smartphones increased $8 over the prior quarter, reaching $143, which is still below average price of $149 in the year-ago quarter.