IDC projects that shipments of Windows Phone will displace Apple iOS to become the number two OS running smartphones in 2016.
Android will retain the top spot, IDC said Wednesday morning.
The growth of iPhone smartphones from Apple will moderate over the five-year IDC forecast because the popular device will have saturated many markets around the world.
During the period, Apple will start having to rely on its customers to replace older iPhone models while searching out new buyers in emerging markets. "Emerging market growth is of utmost importance if iOS is to gain share," IDC said.
The researcher predicts that Windows Phone will gain market share over the five-year period despite its slow start.
Nokia, which is making Windows Phone-based devices, is seen as strong in emerging markets, IDC added.
In 2016, IDC projects that the iPhone's worldwide market share will drop from from 20.5 percent in 2012 to 19 percent. Meanwhile, Windows Phone's share will jump from 5.2 percent in 2012 to 19.2 percent in 2016, IDC said.
Android will continue to hold its top position over the five years, though it's share will decline slightly from 61 percent in 2012 to 52.9 percent in 2016, IDC said.
Android shipments will be dominated by Samsung-made devices, although there will continue to be many Android smartphones from manufacturers such as Motorola, HTC, and LG.
The news for Apple is not all bad, though, because shipment volumes will continue to increase shipment through 2016 despite the decline in market share, IDC noted. That's because the overall smartphone market will continue to grow by 12.7 percent over the five-year period.
Even shipments of the struggling BlackBerry smartphone from Research in Motion will grow by nearly 11 percent over the five years, though its market share will decline slightly from 6 percent to 5.9 percent in 2016, IDC said.
IDC said BlackBerry's market share will barely decline because many customers in emerging markets want affordable messaging devices.
Some 686 million smartphones will ship in 2012, an increase of by nearly 39 percent over 2011, IDC said.
Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at @matthamblen, or subscribe to Matt's RSS feed. His e-mail address is email@example.com.
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This story, "Windows Phone Projected to Overtake iPhone by 2016" was originally published by Computerworld.