Windows 10 Mobile 10586.164 looks like a release candidate for 8.1 upgrades

[Windows Central]

A recent report in Venture Beat noted that official upgrades to Windows 10 Mobile from Windows Phone 8.1 would begin later in March.

Now, a tip from a user running Windows Phone 8.1 on a Lumia 520 and joining the Insider program to go to Windows 10 Mobile shared with a new prompt before the upgrade.

Full story from the WindowsCentral blog...