iPhone 5 Is World's Best-Selling Smartphone

The iPhone 5 is the king of all smartphones — when it comes to unit sales, at least.

The coveted Apple smartphone overtook Samsung's mega-popular Galaxy S III to become the world's best-selling smartphone for the first time ever in the fourth quarter of 2012, according to new research from Strategy Analytics. Apple shipped an estimated 27.4 million iPhone 5 units worldwide in Q4 to capture an impressive 13 percent share of all smartphones shipped globally.

"A rich touch-screen design, extensive distribution across dozens of countries, and generous operator subsidies have been among the main causes of the iPhone 5's success," Neil Shah, senior analyst at Strategy Analytics, said in a statement.

In addition to the success of the iPhone 5, Apple's older iPhone 4S ranked as the world's second most popular smartphone in the fourth quarter. Apple shipped an estimated 17.4 million iPhone 4S units for 8 percent smartphone share globally during the period.

"Apple's iPhone 5 and iPhone 4S together accounted for 1 in 5 of all smartphones shipped worldwide in Q4 2012," Neil Mawston, executive director at Strategy Analytics, said in a statement. "This was an impressive performance, given the iPhone portfolio's premium pricing."

During a January earnings call, Apple said it sold 47.8 million iPhones during the quarter.

The research firm estimated that the Galaxy S III was the third best-selling smartphone model in the fourth quarter of 2012. Samsung shipped 15.4 million Galaxy S III units globally, capturing 7 percent share of the market.

Though the Galaxy S II has been a huge success for Samsung, its popularity "appears to have peaked," Mawston said.

"Samsung will surely be keen to introduce its rumored Galaxy S IV upgrade in the coming weeks to fight back against Apple's popular iPhone range," he added.

Samsung is rumored to be gearing up to launch the Galaxy S IV at an event on March 14 in New York City.

For more from Angela, follow her on Twitter @amoscaritolo.