Microsoft's plans to upgrade older Windows Phones to the latest version of its smartphone OS have been a bit of a shambles so far. But today - following a delay since December, and weeks of inconsistent and inaccurate messaging from both Microsoft and its partners - the company has finally announced details of its Windows 10 Mobile rollout for older devices.
In order to upgrade, you'll need to install the Windows 10 Upgrade Advisor app on your handset, which you can download from the Windows Phone Store here.
Microsoft says that "consistent with our approach to the Windows 10 PC upgrade, we are focused on delivering a high quality experience for our customers", adding: "Our goal is to only offer the Windows 10 upgrade to devices that we are confident can continue to deliver a good customer experience."
The company also points out that "the availability of Windows 10 Mobile as an upgrade for existing Windows Phone 8.1 devices will vary by device manufacturer, device model, country or region, mobile operator or service provider, hardware limitations, and other factors."
So, while the update is beginning to roll out today, you may well have to wait a while longer until it's finally available for your device.