Microsoft says Windows Phone 7 is doing well, with 1.5 million phones carrying the operating system being sold.

The figure isn't as impressive as the Apple iPhone 4, which sold 1.7 million units in just three days earlier this year. But if true, it shows that Microsoft is making a dent in the smartphone market.

A report from Nielsen bears this out, as when the company polled smartphone owners, and those who planned to buy one, found that Windows phones made up some 19% of the total smartphone market.

Achim Berg, vice president of Microsoft's mobile communications business and marketing group, noted the sales in an interview on Microsoft's blog.

The iPhone 4 is still the fastest-selling smartphone, and so far, according to Nielsen, the most popular by a hair. Second and third place go to Android phones and Blackberrys, respectively. But if Berg is right then it shows Microsoft is starting to make up for the high-profile flop of the Kin earlier this year.