To help you visualise where we are in terms of the window for these monthly OS updates, here's a helpful chart:
The Fall Creators Update ("FCU", 'rs3', i.e. 'Redstone 3', at least in name) is the 'production' branch of Windows 10 Mobile, and these are regular 'Patch Tuesday' fix round-ups for it, with the official list for 15254.544, the '2018-12' update' mainly composed of minor fixes and security patches, at least in terms of mobile relevance.
From the official release notes:
- Security updates to Microsoft Edge, Windows apps, Windows graphics, and Windows kernel
This FCU update applies officially to the:
- HP Elite x3, HP Elite x3 (Verizon), HP Elite x3 (Telstra)
- Wileyfox Pro
- Microsoft Lumia 550, Lumia 650, Lumia 950/950 XL
- Alcatel IDOL 4S, Alcatel IDOL 4S Pro, Alcatel IDOL 4 Pro, Alcatel OneTouch Fierce XL
- Softbank 503LV
- VAIO Phone Biz
- MouseComputer MADOSMA Q601
- Trinity NuAns Neo
All of which are fully supported officially, with updates until the end of 2019.
As usual and as per the graphic above (the rectangles in a shade of red), one other supported Windows 10 Mobile branch is getting an update too, so all those older phones (Lumia 930, 830, 735, 640, etc.) finishing life on the Creators Update (if the user was clued up enough to have been on the Insiders Programme for most of 2017) aren't losing out on core security fixes.
You'll spot from my diagram that we reached the end of the update schedule for phones on the Anniversary Update (AU) in November - meaning that anyone with one of these older phones who stayed on 'production' status will now be 'frozen' in time in terms of security. However, looking to the future, don't worry too much if your phone still runs AU (Windows 10 branch 1607) and you're not feeling confident enough to go for our hack [updated link]. Although you'll not get any more OS updates, Windows 10 Mobile is a very small malware target in the grand scheme of things, so you'll be fine as you are. And you'll still get application updates, of course, possibly for years to come.
But the hack is now de rigeur for anyone with one of these older phones who cares about absolute security and the good news is that most geeks who have tried it now have their older phones running the very latest FCU. So give it a try if you're feeling adventurous!
As ever, with all phones, head into Settings/Update & Security/Phone update in order to (try to) get the update immediately.