An anonymous reader writes: One year after Windows 10 Mobile was announced, Microsoft is finally rolling out their new OS to older mobile devices, specifically devices running Windows Phone 8.1. Here's the complete list of supported phones: 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, and the MCJ Madosma Q501. Depending on where you live and which carrier you have, the update will be handled differently. Microsoft has said "many older devices are not able to successfully upgrade without an impact on the customer experience." For an OS that continues to lose market share [to] iOS and Android, it makes sense for Microsoft to be so concerned about the user experience as it is crucial for the success of Windows 10 Mobile.