Microsoft officially unveiled the new operating system, Windows Phone 7 Series, at the Mobile World Congress in Barcelona on February 15, 2010,^[2] and revealed additional details at MIX 2010 on March 15, 2010. The final SDK was made available on September 16, 2010.^[3] HP later decided not to build devices for Windows Phone, citing that it wanted to focus on devices for its newly purchased webOS.^[4] As its original name was criticized for being too complex and "wordy", the name of the operating system was officially shortened to just Windows Phone 7 on April 2, 2010.^[5]

On October 11, 2010, Microsoft's CEO Steve Ballmer announced the 10 launch devices for Windows Phone 7, made by HTC,Dell, Samsung, and LG, with sales beginning on October 21, 2010 in Europe and Australia and November 8, 2010 in the United States. The devices were made available on 60 carriers in 30 countries, with additional devices to be launched in 2011.^[6] Upon the release of Windows Phone 7's "Mango" revision, additional manufacturers became partners, including Acer, Fujitsu, andZTE.^[7]

Windows Phone initially supported twenty-five languages, with applications being available through Windows Phone Store in 35 countries and regions. Support for additional languages and regions were subsequently brought through both the Mango and Tango updates to the OS respectively

Windows Phone 8

On June 20, 2012, Microsoft unveiled Windows Phone 8 (codenamed Apollo), a third generation of the Windows Phone operating system for release later in 2012. Windows Phone 8 replaces its previously Windows CE-based architecture with one based on the Windows NT kernel, and shares many components with Windows 8, allowing developers to easily port applications between the two platforms.

Windows Phone 8 also allows devices with larger screens (the four confirmed sizes are "WVGA 800×480 15:9","WXGA 1280×768 15:9","720p 1280×720 16:9","1080p 1920x1080 16:9" resolutions) and multi-core processors, NFC (that can primarily be used to share content and perform payments), backwards compatibility with Windows Phone 7 apps, improved support for removable storage (that now functions more similarly to how such storage is handled on Windows and Android), a redesigned home screen incorporating resizable tiles across the entire screen, a new Wallet hub (to integrate NFC payments, coupon websites such as Groupon, andloyalty cards), and "first-class" integration of VoIP applications into the core functions of the OS. Additionally, Windows Phone 8 will include more features aimed at the enterprise market, such as device management, BitLocker encryption, and the ability to create a private Marketplace to distribute apps to employees^[8][9]—features expected to meet or exceed the enterprise capabilities of the previous Windows Mobile platform.^[10] Additionally, Windows Phone 8 will support over-the-air updates, and all Windows Phone 8 devices will receive software support for at least 36 months after their release.^[11]

In the interest of ensuring it is released with devices designed to take advantage of its new features,^[12] Windows Phone 8 will not be made available as an update for existing Windows Phone 7 devices. Instead, Microsoft released Windows Phone 7.8 as an update for Windows Phone 7 devices, which backported several features such as the redesigned home screen.

Addressing some software bugs with Windows Phone 8 forced Microsoft to delay some enterprise improvements, like VPN support, until the 2014 release of Windows Phone 8.1.^[13]