Moving a user's audio conferencing provider to Microsoft
To use Audio Conferencing in Office 365 with Skype for Business and Microsoft Teams, users in your organization need to have an Audio Conferencing license assigned to them and their audio conferencing provider must be set to Microsoft. See Try or purchase Audio Conferencing in Office 365 to get more information on licensing and how much it costs.
To move a user's audio conferencing provider to Microsoft
If an Audio Conferencing license is assigned to a user who doesn't have an audio conferencing provider, the user's provider will be automatically set to Microsoft and you don't have to do anything else. If the user already had an audio conferencing provider, you must change the user's provider to Microsoft after assigning them an Audio Conferencing license.
To set Microsoft as the audio conferencing provider for a user that has an Audio Conferencing license assigned but is using another audio conferencing provider, do this:
Sign in to Office 365 with your work or school account.
Go to the Office 365 admin center > Skype for Business.
In the Skype for Business admin center, go to Audio conferencing.
If you see a banner notifying you that there are users who have an Audio Conferencing license assigned but don't have Microsoft set as their audio conferencing provider yet, click Click here to move them. If you don't see the banner, in the Skype for Business admin center click Users, and then select the Users ready to be moved to Audio Conferencing filter.
Select the users you want to move, and then in the Action pane, click Edit.
Select Microsoft in the Provider name list.
When the audio conferencing provider of a user is changed to Microsoft, the audio conferencing information of the user will change. If you need to keep this information, please record it somewhere before changing the provider of any of the users.
What else should I know?
If you select the user in the list, you can view the default audio conferencing information of the user but you won't be able to see the audio conferencing PIN. You can reset the audio conferencing PIN of a user by clicking Reset.
If you want to change audio conferencing settings for a user, you can select the user from the list and then click Edit and make your changes on the Properties page.