Just as Microsoft announced that it was done coding its new Windows Mobile Platform -- dubbed Mango -- Fujitsu of Japan rolled out the first prototype using the anticipated software.

Japan-based Fujitsu, teaming up with mobile carrier KDDI, told press that the two companies would launch the first smartphone based off Mango early in the fourth quarter.

The phone is the first of several handsets that Microsoft hopes will to turn its fortunes and make it a serious player in the smartphone market.

Fujitsu's "IS12T" phone will be both dustproof and waterproof, representatives said, and sport a 13-megapixel camera, among other cutting edge features. Most importantly, it will be the first Windows 7.5 (Mango) powered phone on the market.

The announcement comes just hours after Microsoft said has put the final touches on Mango and released it to manufacturers.

Calling it a 'milestone', Microsoft engineer Terry Myerson said the code was ready to make its way out of the hands of developers into mature production phases, signaling availability would be soon.

"This marks the point in the development process where we hand code to our handset and mobile operator partners to optimize Mango for their specific phone and network configurations," Myerson said.

The software features hundreds of improvements and features, and forms the basis for new Microsoft and Nokia phones. 

Changes include better multitasking, Twitter integration and better browsing with a mobile version of Internet Explorer 9, executives explained in the past.

"We can't wait to get Mango in your hands so you can experience all the new features for yourself," Myerson said.

The company is vying to take back share from the dominant mobile forces, Apple and Google, with its Android Operating system.

Despite the many glowing reviews of Windows 7 Mobile, Microsoft was relegated to the slide lines as the iPhone dominated the market, and new smartphones based off Google's Android ratcheted sales.

Research firm Gartner predicted earlier this year that Microsoft could jump back to the No. 2 for mobile platforms spot as early as 2015 as it gets a boost from the new software and its tie up with Nokia.

The partnership will give Microsoft access to Nokia's massive global distribution chain and allow it to piggy back the world's largest handset maker.

Windows Phone devices will hold only 5 percent of the market in all of 2011, but will jump to nearly 20 percent in 2015, the firm said.

"Here on the Windows Phone team, we now turn to preparing for the update process," Microsoft said. "The Mango update for current Windows Phone handsets will be ready this fall, and of course will come pre-installed on new Windows Phones."

Microsoft first outlined its plans for Mango back in February and shared further details back in May.