The wait is over for owners of Lumia smarthones that have been running the Windows 8.1 mobile OS. Microsoft has to begun the roll-out of Windows 10 Mobile to Windows Phone 8.1 devices. In order to find out if the upgrade is available for your device, check the Upgrade Advisor app.

Below you see the current list of Windows Phone 8.1 devices that are supported for the upgrade to Windows 10:

Lumia 1520, 930, 640, 640XL, 730, 735, 830, 532, 535, 540, 635 1GB, 636 1GB, 638 1GB, 430, 435, BLU Win HD w510u, BLU Win HD LTE x150q, MCJ Madosma Q501

Of course, this list includes a limited set of Windows Phone 8.1 devices and does not include some devices that are currently running Windows 10 Mobile in the Windows 10 Mobile Insider program. As Windows 10 delivers new features, many older devices are not able to successfully upgrade.

Windows Insiders already have the latest build in their devices and do not need to downgrade to Windows Phone 8.1 to receive any updates.

If you already have the Windows 10 Mobile Insider Preview build on your device but it is not on the list of devices that will receive a formal Windows 10 update, you may keep using your device in an unsupported state. Microsoft will not be offering build updates beyond the Current Branch build 10586. At some point in the future these devices will also stop receiving updates to the Windows 10 Mobile Insider Preview build.