Microsoft has launched the latest version of its mobile phone operating system, called Windows Phone 7 series.

The software has a redesigned user interface and incorporates many Microsoft services such as Xbox LIVE games and the      

The software was introduced at an event at the Mobile World Congress in Barcelona.

According to research firm Canalys, Microsoft's software currently has around 9% of the smartphone market.

That puts it fourth in the global market behind Symbian, Rim (makers of the Blackberry) and Apple's iPhone OS.

The new system follows the launch of Windows Mobile 6.5 in October 2009.