The research firm's US data shows that Windows Phone handsets accounted for 4.1 percent of all smartphone sales in the three month period ending 13 February 2013.
That's up significantly against the same period last year, when Windows Phone accounted for just 2.7 percent of sales.
BlackBerry, meanwhile, accounted for just 0.7 percent of smartphone sales in the three months ending 13 February 2013.
That's a troubling decline against the 3.6 percent of sales it captured in the same period last year, although it's worth noting that BlackBerry 10's US launch occurred after these figures were collected, and the company-formerly-known-as-RIM may still hold a larger share of the US market.
Top heavy
Unsurprisingly, Android remains the most popular OS overall, with Google's mobile operating system capturing 51.2 percent of US smartphone sales for the period.
iOS, meanwhile, accounted for 43.5 percent of smartphone sales down against 47 percent in the same quarter last year.
So while things remain relatively stable at the top, Microsoft's gains represent sizeable growth for the company.
Its share of smartphone sales represents growth of 52 percent against the previous year, making it the fastest growing OS in the region.
[source: Kantar Worldpanel]
