Microsoft on said that it had finished the development of its anticipated mobile phone software, dubbed Mango, as it vies to catch up to the iPhone and Android.
On Tuesday the world's largest software company said the first update to its Windows 7 mobile platform has been released to manufacturers.
"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," Microsoft 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.
The company is vying to take back share from the dominant mobile forces, Apple and Google, with its Android Operating system.
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.