Microsoft chief Steve Ballmer on Tuesday unveiled his company's line of Windows smartphones in an offensive against Apple's iPhone and Google's Android system.

Around 30 types of "Windows phones" with various designs will be available by the end of the year in more than 20 countries.

Seven phone-makers, including Sony, Samsung and Toshiba, and 16 operators including Orange, Vodafone and T-Mobile, are involved in the launch.

The phones, which combine the ability to make calls, surf the Internet and view videos, carry Microsoft's Windows Mobile 6.5 operating system.

"We have done a lot of work on the user interface, we simplified the user interface," Ballmer told a news conference at Microsoft's new French headquarters near Paris in Issy-les-Moulineaux.

"We have taken the Internet Explorer browser technologies, and we rebuilt them for the first time for these Windows phones. So you can get the same experience on these phones that you will get on your windows PC," he said.

Full story: Yahoo News