In Microsoft Skype for Business 2016, users who are configured as Teams-only experience the following functionality:
When they open the Skype for Business client, they see that they are in a limited functionality mode, and they are directed to the Teams client.
They might still see the option to schedule Skype for Business meetings in Microsoft Outlook.
They can still successfully schedule Skype for Business meetings.
The Skype Meeting Add-in for Microsoft Office option can be left as enabled, or it can be reenabled. This provides the ability to schedule Skype for Business meetings in Outlook. The Skype for Business client does not block meeting scheduling requests if a user is set up as Teams-only.
To fix this issue, install the July 7, 2020, update (KB4484326) for Microsoft Skype for Business 2016.
After you install this update, the Skype Meeting Add-in for Microsoft Office no longer shows UI options in Outlook if the Skype for Business client is in limited functionality mode. After a user is configured as Teams-only, Outlook must be restarted for the UI options to be removed. If the UI options are still available in Outlook, but the Skype for Business client is in limited functionality mode, the following situation exists: A user can still try to schedule a Skype for Business meeting, but the attempt will fail.
For more information, see Understand Microsoft Teams and Skype for Business coexistence and interoperability.