Between the launch date of the Microsoft Lumia 950XL and comments made by Microsoft’s official Lumia Facebook account, we now know when Microsoft’s Windows 10 Mobile will roll out. 

Microsoft said Tuesday that the company plans to launch the its new Lumia 950XL and Lumia 950 “in November,” according to a slide shown during Microsoft’s launch event. Microsoft exhibited those phones running with Windows 10 Mobile (which Microsoft sometimes simply calls Windows 10), and they’re expected to ship with what is presumed to be the final version of the OS.

On Wednesday and again on Thursday, Microsoft took to its Facebook page to clarify the dates on which older phones could receive Windows 10.

“Windows 10 is available on PCs and tablets now, and while Lumia 950 and Lumia 950 XL ship with Windows 10 for phones, broad availability of Windows 10 on other devices, including mobile phones, will begin rolling out in December,” the official Lumia account wrote.

Why this matters: With just a tiny fraction of the smartphone market, Microsoft needs to convince consumers to upgrade, and the combination of the new Lumia phones and its latest smartphone OS is the most potent option it has. As Brad Sams at noted, however, it’s possible that customers with older Windows Phone devices will simply choose to upgrade to the latest phones instead.