Microsoft has officially dropped support for Windows Phone 8.1, its last mobile OS under the Windows Phone moniker.
End of support for Windows Phone 8.1 means the few smartphones still running the OS won't receive any more security or feature updates, or any other form of support.
Windows Phone 8.1 launched three years ago as the third and final generation of Windows Phone since 2010. The Windows Phone brand was succeeded by Windows 10 Mobile.
Today, fewer than one percent of the world's smartphones run on Windows Phone. Despite exceeding 10 percent market share in some European markets, worldwide it never got close to challenging the Android and iOS duopoly.
At the time it acquired Nokia's handset business for $7.2bn, Microsoft was betting Windows Phone would be running on 15 percent of the world's smartphones by 2018. Analyst IDC effectively pronounced Microsoft's mobile platform dead in 2015 due to a lack of support from OEMs.
According to AdDuplex, nearly 75 percent of Windows phones are running Windows Phone 8.1, with 20 percent running Windows 10 Mobile. The newer OS's share has increased but the ad analytics firm says this growth is probably because Windows Phone 8.1 users are abandoning their phones for Android or iOS rather than any rise in sales of Windows 10 Mobile devices.
Those still running Windows Phone 8.1 have already been cut off from major apps, such as Facebook Messenger, which lost support earlier this year. Even Microsoft's Skype dropped support for the OS when it rebuilt it as a Universal Windows Platform app for Windows 10.
Microsoft did offer Windows 10 Mobile to some Windows Phone 8.1 devices last year and an even narrower subset received the Windows 10 Creators Update in April.
Despite Microsoft appearing to have abandoned its mobile ambitions, Microsoft CEO Satya Nadella recently said it could make a new mobile device one day but not one that looks like today's smartphone.