On January 21, 2015, Microsoft announced the release of their first Interactive whiteboard, Microsoft Surface Hub (part of the Surface family). On July 29, 2015, Microsoft released the next version of the Windows operating system, Windows 10. The successor to Windows Phone 8.1, Windows 10 Mobile, was released November 20, 2015. In Q1 2015, Microsoft was the third largest maker of mobile phones selling 33 million units (7.2% of all), while a large majority (at least 75%) of them do not run any version of Windows Phone those other phones are not categorized as smartphones by Gartner in the same time frame 8 million Windows smartphones (2.5% of all smartphones) were made by all manufacturers (but mostly by Microsoft). Microsoft's share of the U.S. smartphone market in January 2016 was 2.7%.