In Microsoft Skype for Business 2016, assume that you clear the Also ring option under Secondary Ringer in Audio device settings. Then you sign out and restart the Skype for Business 2016 client. You may find the Also ring option is still checked and rings during an incoming call.
Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.
To fix this issue, install the May 29, 2019 update for Skype for Business for a Click-to-Run installation. To do this, open an Office program, such as Word, and then select File > Account > Update Options > Update Now.
Note If "Update Options" does not exist in the client, this is an .msi installation.
Don’t see your Skype for Business client in the list? Click here for a complete list of clients. Click-to-Run is the recommended way to install the Skype for Business client. You can download the Click-to-Run client from the Office365 Portal.
After you apply the update, create a Group Policy to set the following registry key on clients:
DWORD data: 1
Alternatively, you can enable this fix by creating a custom policy entry and adding it to the client policy, as follows: