Karbonn and Lava can now use cheaper and soft keys to make Windows Phone-based mobiles and also adapt designs from their Android phone equivalents.

Microsoft has started its biggest push yet to make its Windows Phone software more popular in emerging markets with the induction of domestic mobile phone players Xolo and Karbonn as partners who will make smartphones that use the company’s trademark mobile software.

This push, which is one of the first moves by the company after newly appointed CEO Satya Nadella took over, is also accompanied by several changes in the company’s policy towards these partners. For instance, Microsoft is easing several restrictions on how phone makers use its software, in a bid to encourage them to drive down costs.

“We’re open for business on Windows Phone to anyone who wants to build a Windows phone,” said Nick Parker, Senior Vice President for mobile makers, while addressing reporters at the Mobile World Congress trade fair here.

The other new partners include South Korea’s LG Electronics and China’s ZTE, Lenovo and Gionee.

These sweeping changes also come on a day when Nokia, which Microsoft will finish acquiring later this quarter, decided to bring out an Android-based line of smartphones.

One of the major restrictions that Microsoft had earlier imposed, which hampered domestic players like Karbonn, was on how the hardware layout of the phone should be manufactured.

With this restriction now gone, Karbonn and Lava can now use cheaper and soft keys to make Windows Phone-based mobiles and also adapt designs from their Android phone equivalents.