Windows Phone 8.1

Abstract is: Windows Phone 8.1 was the third generation of Microsoft's Windows Phone mobile operating system, succeeding Windows Phone 8. Rolled out at Microsoft's Build Conference in San Francisco, California, on April 2, 2014, it was released in final form to Windows Phone developers on April 14, 2014 and reached general availability on August 4, 2014. All Windows Phones running Windows Phone 8 can be upgraded to Windows Phone 8.1, with release dependent on carrier rollout dates. Windows Phone 8.1 is also the last version that uses the Windows Phone brand name as it was succeeded by Windows 10 Mobile. Some Windows Phone 8.1 devices are capable of being upgraded to Windows 10 Mobile. Microsoft delayed the upgrade and reduced the supported device list from their initial promise. Support has ended for Windows Phone 8.1 on July 11, 2017.