Windows Phone version history

Windows Phone 7.5 {{anchor|7.5}}

At the 2011 Mobile World Congress, Steve Ballmer announced a major update to Windows Phone 7, Windows Phone 7.5 (codenamed Mango), due toward the end of the year. The update addressed platform shortcomings with a mobile version of Internet Explorer 9 supporting desktop-level web standards and graphics, third-party app multitasking, Twitter integration in the People Hub, and Windows Live SkyDrive access. Although the OS identifies internally as version 7.1, it is marketed as version 7.5 to end-users.

Microsoft began rolling out Windows Phone 7.5 to the United States and international markets on September 27, 2011, with the first pre-loaded phones appearing in the last quarter of 2011. A minor 2012 update called Tango lowered hardware requirements to support 800 MHz CPUs and 256 MB of RAM, disabling some resource-intensive features and blocking installation of demanding apps, enabling lower-cost devices for emerging markets like China.

Windows Phone 8

General Distribution Release 1 (Portico) for Windows Phone 8 rolled out in December 2012, bringing messaging enhancements, more efficient Bluetooth connectivity, and an always-on WiFi setting. General Distribution Release 2 began rolling out in July 2013, with Nokia releasing its own Lumia Amber firmware update for Lumia phones, improving cameras and fixing bugs. On October 14, 2013, Microsoft released the third General Distribution Release update, which rolled out over following months; Windows Phone Developers received it first under a new Developer Preview Program.

Windows Phone 8.1

General Distribution Release 1 (Update 1) for Windows Phone 8.1 added new language and region support for Cortana, the ability to organize apps into folders on the Start Screen, SMS forwarding of multiple messages, improvements to Xbox Music, a live tile for the Windows Phone Store, and application sandboxing. It also introduced new VPN and Bluetooth features for enterprise users, support for interactive cases like HTC's Dot View case, larger phablet screen resolutions (1280x800, 540x960 qHD, 1280x768), and Qualcomm QuickCharge 2.0.

Internet Explorer Mobile changes moved away from open standards to adopt non-standard features from Safari and Chrome, implementing browser detection, improved rendering via legacy WebKit feature detection, HTML5 support, and fixes for bad HTML code. Information about GDR2 (Update 2) released in February 2015 indicated increased OEM security, extra languages, additional technology support, and an anti-theft mode.