Microsoft CEO Steve Ballmer has admitted that the Windows Phone platform has struggled to gain traction in the mobile OS market, almost year after it was launched.

After celebrating the monumental success of 400m Windows 7 PC licenses sold, Ballmer revealed that the mobile side of the business still has a long way to go to make a name for itself.

He told the company's Worldwide Partner Conference in LA: "Phones? We've gone from very small to very small but it's been a heck of a year.

"And you're going to see a lot of progress in that competitive market this year," he added.

Bring on Mango

It is estimated that Windows Phone, despite producing what is widely regarded as an excellent OS with a host of top manufacturers on board, has only managed to pick up 1 per cent of the market.

Later this year the company will provide the Mango update for all users which will boast 500-plus changes.

The first Nokia-built Windows Phone device will also arrive later this year, a partnership which is considered integral to the continued success of both entities.