Deliveries of smartphones like Apple's iPhone are expected to increase 55 percent this year, four times as fast as the wider phone market, IT research firm IDC said.

IDC said Thursday growth would be fueled by lower prices, better features and cheaper data plans, with growth particularly pronounced in emerging regions of Asia and Latin America where adoption was still in its early days.

"Mobile phone users around the world are turning in their 'talk-and-text' devices for smartphones as these devices allow users to perform daily tasks like shopping and banking from anywhere," said Kevin Restivo, senior research analyst with IDC's Worldwide Quarterly Mobile Phone Tracker.

IDC expected Google's Android smartphone operating system, which passed Nokia's Symbian as the leading operating system worldwide at the end of last year, to grow to more than 40 percent of the market in the second half of 2011.

IDC said Symbian, being ditched by Nokia in favor of Microsoft's Windows Phone software, would steadily lose share.

It predicted Nokia Windows phones could capture more than 20 percent of the smartphone market in 2015, if the Nokia-Microsoft integration goes smoothly.

(Reporting by Georgina Prodhan; Editing by Dan Lalor)