MS's business sector proposition had a reasonable position in the market. The market was fragmented to bits then as well. A lot of it was Symbian and WinCE stuff with some fallout from proprietary platforms and the POS that was J2ME.
They let that go with WP7 and to iOS a bit (c'mon it's a version 1 product) but are clawing it back now with WP8.
Not one business person I know uses Android anymore though citing it's unreliable. I see a rough distribution of 70/30 iOS/WP8 and that's falling because dropping an iPhone is an expensive problem to sort for corporate IT departments and individual users. You can afford to throw away a couple of WP8 devices a year for the same cash per user as a 4S and 4 WP8 handsets for the price of a 5.