Worldwide Sales of Smartphones is expected to increase 55 percent in 2011 according to IDC's Worldwide Quarterly Mobile Phone Tracking report. The firm predicts 472 million smartphones will be shipped in 2011 compared to roughly 305 million units shipped in 2010

Smartphone sales are expected to nearly double from 2011 to 982 million units by the end of 2015.

Also in 2011, smartphone shipments will grow more than four times the rate of overall cellphone shipments, thanks to falling average selling prices, increased functionality, and lower-cost data plans that, among other factors, make the devices more accessible to a wider range of consumers, said senior research analyst Kevin Restivo. Smartphone growth is "particularly pronounced" in emerging markets where adoption is still in its infancy, he said.

IDC predicts that Android based smartphones will continue to be the top sellers from 2011 to 2015 increasing their estimated marketshare from 39% in 2011 to 43% in 2015. The firm also predicts sales smartphones based on Windows Mobile platform will increase by a whopping 82% per year increasing Microsofts market share from under 4% in 2011 to over 20% by 2015.

In IDC's vision of the future, Apple's iOS platform and RIM's BlackBerry platform are expected lose a small amount of market share during the 2011 through 2015.

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