Phones running the Windows operating system haven't exactly set the marketplace on fire. In the second quarter of this year, 7.4 million phones running Windows were sold, according to Gartner Research. That's a long way behind the No. 2 system, Apple's iOS, with 31.9 million phones sold in that time.
But Nokia has squarely positioned itself as the leading vendor of those Windows phones, making 82% of the devices sold last year. In 2011, Windows and Nokia announced a partnership in which Nokia switched to the Windows OS as the default system running all of its handsets.
That hasn't been enough to put Nokia on super-solid ground, at least not yet. But the longstanding partnership is what led to Monday's purchase, and if having in-house hardware gives Windows Phone a boost, Microsoft and Nokia will reap the rewards.