I have ran into a particular issue a few times when activating phone numbers in Skype for Business Online Phone System. If you don’t look in the right place, you might be left scratching your head as to what the problem is. The user will be assigned a phone number using the Set-CsOnlineVoiceUser command but will not be able to make or to receive calls over the PSTN. In these cases I have looked at, the user’s licensing is all correct. If you run Get-CsOnlineVoiceUser for the person, it will show the phone number is assigned and will give a nice warning about the issue

Read my full article over at the Perficient Microsoft Blog: