Microsoft's head of Windows phone marketing announced the sales figure and said they were in the expectations ballpark.

"Sales are ramping well ... and are in line with our expectations, especially when compared to other new platform introductions," said Achim Berg, a Microsoft vice president of business and marketing for Windows phones, in a Q&A posted on the company's .

Berg called Microsoft's expectations for WP7 "realistic," and like the company's CEO, Steve Ballmer, said the new OS was essentially a do-over.

"We started fresh with Windows Phone 7, and it's a different kind of phone. Measuring for success is more long term than short term," Berg said. "[But our] numbers are similar to the performance of other first generation mobile platforms."

The 1.5 million figure does not necessarily mean that many consumers have a WP7-based device, since manufacturers typically sell their handsets to mobile carriers, who in turn re-sell the .