Nokia’s Smartphones currently come with Symbian that has no many fans any more; many users change to Android phones.

Nokia is now contracted with Microsoft to use Windows Phone, both of them could gain a lot advantages from each other.

Here could be the reasons:

In a nutshell, IDC is assuming that all Nokia users will stay loyal to the brand and become Windows Phone 7 users. (via TechRepublic.com)

In the next four years, the biggest shift will come from Nokia’s Symbian, which IDC predicts will drop from 20.6 percent to 0.1 percent as the company switches over to the Windows Phone platform. Microsoft will see big gains from its deal with Nokia, jumping up from 3.8 percent in 2011 to 20.3 percent in 2015. (via AppleInsider.com)

Checkout detail here:

• March 2011: By TechRepublic
• June 2011: By AppleInsider

It’s just a predict that could be a bit different in the future, let’s see how 3 main OS competition: Android, Microsoft and iOS.