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Dropbox has announced availability on Windows Phone devices and Microsoft tablets, available on Windows RT, 8.1, and Windows Phone 8.0.

Windows now completes the set of mobile options for Dropbox, with the cloud storage product already available on Android phones, Kindle Fire, iPhones, iPads and BlackBerry phones.

The news comes as both companies look to solidify their partnership established in November last year. At the time this publication questioned the decision given Microsoft’s strong play on its own cloud storage product, OneDrive, now available unlimited to Office 365 subscribers.

Yet it makes more sense underneath the surface; Dropbox will look to gain a foothold in the enterprise market, while Microsoft looks for assurances it can ‘play nicely’ with other vendors. The announcement could also be seen as a timely one given Box’s imminent IPO.

Picture credit: Dropbox

This isn’t the only recent announcement Dropbox has made. Earlier this week the San Francisco based firm announced the acquisition of CloudOn, a mobile cloud collaboration tool.

“We’re taking the next step toward our vision of reimagining docs – by joining the Dropbox team,” CloudOn wrote in a blog post. “Our companies share similar values, are committed to helping people work better, and together we can make an even greater impact.”

At the time of the CloudOn acquisition, pundits questioned the Microsoft and Dropbox partnership. Forbes columnist Ben Kepes wrote: “[Office and Dropbox] is one partnership that never quite gelled in my mind – Microsoft has, after all, its own file sharing solution. With this acquisition, one wonders whether Redmond will consider its cosy relationship with Dropbox.”

Today’s announcement seems to change that. You can read the Dropbox blog post here.