December 2017 update for Windows 10 Mobile comes with build 15254.124
Phones on Creators Update and Anniversary Update also receives updates
Microsoft has released new updates to supported smartphones on the various branches of Windows 10 Mobile. Devices running the latest version (Fall Creators Update – feature2) should see build 15254.124 in the Windows Update page. Smartphones on the Creators Update (like the Lumia 640) will receive build 15063.786, while phones on the Anniversary Update (Lumia 1520, 920) will be updated to 14393.1944.
All these updates bring nothing but regular bug fixes and security improvements. According to the changelog for build 15254.124, phones running the Fall Creators Update get some security updates to Microsoft Edge.
Microsoft will be supporting the latest branch of Windows 10 Mobile until Q4 2019, which means if you own a Lumia 950 you could expect monthly cumulative updates for two years from now.
At the same time, the Windows Insider program for mobile devices is shrouded in mystery. Microsoft’s representative commented on Twitter in November that the program would continue for Windows 10 Mobile, but we have not seen a new build for over a month.