From the Windows blog:
We have released Windows 10 Mobile Insider Preview Build 15223 to in the Fast ring. This build is just one builder newer than last week’s Mobile build and includes the following fixes and improvements:
- We fixed an issue where only the first VPN profile was being displayed in the VPN settings page via Settings > Network & wireless > VPN.
- We fixed an issue where a meeting Time Zone was garbled in Chinese or Japanese.
- Based on Insider feedback, we have changed “Phone Update” to “Windows Update” under Settings > Update & security.
I should emphasise that the quoted changelog represents UI-level or major points fixed and that there are always small under-the-hood OneCore and UAP improvements and fixes which are too low-level to report in the Microsoft post.
See my feature on upgrade paths for the various classes of existing W10M handsets and the wider grid covering older devices, even though most of these won't be able to take advantage of this (RS2+), even with the Insider programme.
Anyone with an existing phone that's officially deemed Windows 10 Mobile CU-compatible by Microsoft can join in the fun - in theory. In each case:
- Head into Settings/Update & Security/Windows Insider Programme.
- Join the Insiders programme and choose the 'Fast' level in the pick list.
- Within a few hours your phone should be seeing the build mentioned above and you'll be running the Creators Update and beyond...
Note that the popular Lumia 930 and 1520 haven't yet been 'provisioned' for this branch of Windows 10 Mobile. I tried - setting the Insider level to 'Fast' doesn't show up any of the recent 152xx builds. Do ping me if this changes, but I'm prepared at this point to say that these 2014/2015 phones may have reached their end on the Creators Update Release Preview ring, which will see critical updates through 2017 and then... no more after that.
See also my Windows 10 Mobile and the Future...