SAN JOSE, Calif. – Acer Inc., Fujitsu Ltd. and ZTE Corp. will make smartphones using Windows Phone 7. The news comes as Microsoft previewed Mango, the next version of the software set to ship this fall.

The three new OEMs join Dell, HTC, LG and Samsung who launched in 2010 the first handsets with the software. Microsoft has also partnered with Nokia, the world's largest cellphone maker, who has embraced Windows Phone 7 as its primary smartphone platform as part of a corporate turnaround.

The Mango version of Windows Phone 7 continues Microsoft's efforts to put mobile applications in the background. Instead the software focuses on functions such as music, video, social networking and individuals and groups of people with apps and their functions emerging as they become relevant.

The concept was first pioneered by the former Palm with its WebOS and Pre handsets and is used by both companies to counter Apple's iOS and Google's Android which sport more third-party app support. Microsoft said its Windows Phone Marketplace now hosts 17,000 apps.

Microsoft is in fifth place with an estimated nine percent share of the smartphone operating system market in 2010, according to an upcoming report from Forward Concepts (Tempe, Ariz.). It will expand to an 11 percent share in 2015 but remain in fifth place behind Symbian, Android, iOS and RIM, the market watcher predicts.

The Mango software will have built-in voice-to-text and text-to-voice support. It also supports a version of the Internet Explorer 9 browser supporting both HTML5 and hardware acceleration.

Microsoft pledged to support 15 new languages on Windows Phone 7 to including Brazilian Portuguese, Simplified and Traditional Chinese, Finnish, Japanese, Korean, Norwegian, and Russian and expand the list of countries where consumers have access to its online app store.