Global smartphone sales are expected to reach 468 million units in 2011, a 57.7% increase from 2010, according to a new report by Gartner.

The report revealed that by the end of 2011, Android will move to become the most popular OS worldwide and will build on its strength to account for 49% of the smartphone market by 2012.

Gartner said that the sales of open OS devices will account for 26% of all mobile handset device sales in 2011, and are expected to surpass the 1 billion mark by 2015, when they will account for 47% of the total mobile device market.

Apple iOS is expected to remain the second biggest platform worldwide through 2014 despite its share deceasing slightly after 2011, this reflects on the assumption that Apple will be interested in maintaining margins rather than pursuing market share by changing its pricing strategy.

According to the report iOS share will peak in 2011, with volume growth well above the market average, which will be driven by increased channel reach in key mature markets like the US and Western Europe.

However, Research In Motion (RIM) share over the forecast period will decline, reflecting the stronger competitive environment in the consumer market, and increased competition in the business sector.

Gartner predicts that Nokia will push Windows Phone well into the mid-tier of its portfolio by the end of 2012, driving the platform to be the third largest in the worldwide ranking by 2013.

The research firm has also revised its forecast of Windows Phone’s market share upward, solely by virtue of Microsoft’s alliance with Nokia.

Gartner principal analyst Roberta Cozza said by 2015, 67% of all open OS devices will have an average selling price of $300 or below, proving that smartphones have been finally truly democratised.

"As vendors delivering Android-based devices continue to fight for market share, price will decrease to further benefit consumers," Cozza said.

"Android’s position at the high end of the market will remain strong, but its greatest volume opportunity in the longer term will be in the mid- to low-cost smartphones, above all in emerging markets."