Steve Ballmer will announce Microsoft's new mobile phone operating system, Windows Mobile 7, on Monday at Mobile World Congress in Barcelona multiple sources have now confirmed.

While for most of the phone industry it was seen as a given that the Redmond based company would be using the show to highlight its latest OS efforts for Windows Phones, the Wall Street Journal and Bloomberg in the US are now reporting it as fact rather than rumour.

"On Feb. 15, Microsoft will unveil its latest effort to get back into the game. The renamed Windows Phone operating system, set to be introduced at the Mobile World Congress in Barcelona, will “move the bar forward,” said Robbie Bach, president of the company’s entertainment and devices division," claims Bloomberg while Wall Street Journal quotes its usual "people familiar with the matter" mantra before spilling the beans:

"At a wireless industry conference in Barcelona on Monday, the company plans to publicly show a new version of its cellphone operating system, Windows Mobile 7, for the first time, according to people familiar with the matter."

The OS (operating System) has long been rumoured to be the merging of the company's current offering Windows 6.5.3 with its Zune MP3 player interface.

Only last week Microsoft announced a stop gap OS update; version 6.5.3, which hasn't actually shipping on a handset yet, suggesting that although an announcement is imminent it maybe some time before we see it in actual handsets.

Microsoft's official MWC press conference will be on Monday night. 

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