(AP) -- Global smart phone sales nearly doubled in the third quarter, and Apple is now one of the top five bestselling manufacturers, a new study finds.

Research firm Gartner said cell phone manufacturers sold 80.5 million smart phones in the third quarter. Smart phones now account for nearly 1 in 5 of all phones sold.

By year's end, Gartner said, smart phone growth will grow 30 percent over last year, although it's unclear to what extent people will buy tablets instead of in 2011.

Gartner's statistics say something about the iPhone's momentum, in particular. Although Nokia Corp., Co. Ltd. and LG Corp. maintained their rankings as the top three cell phone makers, Apple Inc. broke into the top five for the first time, surpassing BlackBerry maker Ltd. for fourth place.

As of October, the iPhone is available in 89 countries and is sold through 166 phone companies.

As popular as the iPhone has become, however, it is not the world's best-selling smart phone. Phones running Symbian software, which comes loaded on many Nokia devices, are the most common in the world, followed by phones running Google Inc.'s Android software.

While Apple's software only runs on the iPhone, which is only available only through AT&T Inc. in the U.S., offers its Android software to many cell phone manufacturers, including HTC Corp., Motorola Inc. and Samsung. Those manufacturers, in turn, make their phones available through a host of cell phone companies. Android phones took the No. 2 spot largely because they had more opportunities to reach consumers.

Google's success in the smart phone market appears to have come at the expense of several formidable competitors - namely, Apple, RIM and Nokia. Phones running Linux-based operating systems dropped out of the top five altogether, while phones running Microsoft's business-grade Windows Mobile software dropped to fifth from fourth.

Google's third-quarter market share rose to 25.5 percent from 3.5 percent last year. The , RIM's BlackBerrys and Nokia phones running Symbian all lost market share, even though these companies each sold more phones in the third quarter than they did at this time a year ago.

Of all the phone companies that sell Android phones, Verizon Communications Inc. fared particularly well. Phones running accounted for 75 percent to 80 percent of the wireless provider's third-quarter smart phone sales, according to Gartner.

Last week, research firm IDC reported that the smart phone market grew 90 percent in the third quarter. It, too, reported that Nokia lost market share since this time last year, even as it sold more phones.