We recently purchased several Polycom VVX 411 phones to use with Skype for Business Online. However, we discovered it didn’t work right out of the box. Turns out, it requires a firmware update (which tipped me off since Skype for Business was still referred to as Lync on the phone). Fair enough, however, even after updating to the latest version (5.9) it STILL didn’t work. We would get stuck at “Unable to fetch user certificate” (or some variation thereof). What could be going on? Well, it turns out 5.9 isn’t yet supported by Microsoft (as of Jan 30th, 2019), so Skype for Business Online won’t work. The second latest version, 5.8.2, does work. So, if you are having trouble with the phone and signing into Skype for Business Online, try updating the firmware (or downgrading) and try again.