Windows Phone 7 Series, unveiled at Mobile World Congress, is Microsoft's latest attempt to build a smartphone operating system.
Steve Ballmer, chief executive officer at Microsoft, said at the launch, "In a crowded market filled with phones that look the same and do the same things, I challenged the team to deliver a different kind of mobile experience."
Every Windows Phone 7 Series phone will come with a dedicated hardware button for Bing, providing one-click access to search. There is also a dedicated Microsoft apps store.
The operating system introduces the concept of "hubs", which bring together activities in a single user interface. Microsoft has built a hub for social networking, one for music and video, and one for games which links into the XBox 360 community.