Microsoft earlier this month reminded owners of devices powered by Windows 10 Mobile that support will end 10 December, although some services may remain active for months after that expiration date.
In a support document revised three weeks ago, Microsoft also told Windows 10 Mobile customers to now steer for Android or iOS smartphones.
"As of December 10, 2019, Windows 10 Mobile users are no longer eligible to receive new security updates, non-security hotfixes, free assisted support options, or online technical content updates from Microsoft for free," the Redmond, Wash. developer said in the support document.
The end-of-support was not completely unexpected.
Previously, Microsoft had said it would support each version of Windows 10 Mobile - initially Mobile was upgraded every six months, just like the desktop OS - for "a minimum of 24 months."
The last Windows 10 Mobile feature upgrade was tagged 1709 in Microsoft's now-familiar yymm format and issued in October 2017.
Just before Windows 10 Mobile 1709 launched, Microsoft's Joe Belfiore, then the company's top phone executive, acknowledged the obvious: "...building new features/hw ((hardware)) aren't the focus," he said of the OS and the decision to withdraw from hardware design and sales.
In the revised support document, Microsoft urged anyone still carrying a Windows 10 Mobile device to dump it for something that runs Google's Android or Apple's iOS. "We recommend that customers move to a supported Android or iOS device," the firm said.
It's not an everyday occurrence for Microsoft to exhort customers to switch to software not created by its own engineers.
But even though security and non-security updates will cease as of 10 December, some services tied to Windows 10 Mobile and the its devices will remain active after that date.
"Automatic or manual creation of new device backups for settings and some applications will continue for 3 months, ending March 10, 2020," Microsoft said.
Other actions, including uploading photos to online storage and restoring a device from existing backup "may continue to work for up to another 12 months from end of support," or until late 2020 ((emphasis added)).
One sign of Microsoft's seriousness in ending support was its acknowledgement that commercial customers - who are often shielded from Microsoft's most painful changes - will be cut off at the same time as consumers.
The finality of support was anticlimactic after the earlier drama of Microsoft's foray into smartphones and its quick - in corporate terms - retreat.
Less than two years after announcing the acquisition of Nokia's phone assets - and little more than a year after that deal was finalised - Microsoft effectively admitted the move was a disaster when it wrote off $7.6 billion.
Along with the enormous charge against earnings, Microsoft began laying off thousands of workers, most of them inherited from Nokia.
Microsoft stayed in the smartphone business but only after significantly scaling back. Even that strategy was unsustainable. By early 2017, the firm's phone revenue plummeted to near zero.
Later that year, Belfiore announced that all development on Windows 10 Mobile had ceased.