The next version of Nokia's Symbian OS will be called Nokia Belle, the company said in a blog post on Wednesday.

Since Nokia made the decision to go with Microsoft's Windows Phone, the company has made a number of Symbian-related announcements. Symbian is important to Nokia because the company is dependent on the sales of Symbian-based smartphones until it ships larger volumes of Windows Phones, which won't be until next year.

"The announcement underlines the difficulties Nokia is having when trying to convince consumers to buy Symbian-based phones, and that the company thinks Nokia is a stronger brand" said Ben Wood, director of research at CCS Insight.

Consumers bought 19.5 million Symbian-based smartphones during the third quarter, giving the OS a 17 percent market share. That compares to 29.5 million units and a 36.3 percent market share during the same period in 2010, according to market research company Gartner.

That still makes it the second largest smartphone OS, after Android. Smartphones based on Symbian are still popular in Eastern Europe and the Middle East, Gartner said.

The blog post doesn't elaborate on why Nokia made the change, and the company didn't reply to questions concerning the thinking behind the move.

Earlier this year, Nokia also decided to abandon its Ovi mobile services brand.

Upgraded versions of the phone models N8, C7 and C6-01 have now started their journey from the factories to the shops with Nokia Belle preinstalled, arriving first in China, then around the world, according to the blog post.

Starting in February 2012, Nokia will release the software update to existing customers, it said.

Belle was announced in August, and includes more home screens, which have been increased from three to six, and a pull-down menu to access notifications.

Widgets for email, music, favorite contacts and the calendar have also been redesigned and now come in five different sizes. The lock screen will tell users about missed calls, inbox messages and other information. Nokia has also improved the user interface for multitasking, it said at the time.