Microsoft has launched the latest version of its mobile phone operating system, the Windows Phone 7 series, the BBC has reported. The new OS, which was unveiled at an event at the Mobile World Congress in Barcelona, has a redesigned user interface and incorporates many Microsoft services such as Xbox LIVE games and the Zune music service. The new system follows the launch of Windows Mobile 6.5 in October 2009. According to research firm Canalys, Microsoft's software currently has around 9% of the smartphone market, which ranks it fourth in the global market behind Symbian, Rim (makers of the Blackberry) and Apple's iPhone OS.