Symptoms
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.
Resolution
To fix this issue, install the May 7, 2019, update (KB4464532) for Microsoft Skype for Business 2016.
Note
Before you apply this update, make sure that you create a GPO to add a new DWORD registry key DisableSecondaryRingerEnablingByDefaultForHeadset and set the value to 1 in the path:
Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Lync
Alternatively, you can enable this by creating a custom policy entry and add it to the client policy:
$x = New-CsClientPolicyEntry -Name "DisableSecondaryRingerEnablingByDefaultForHeadset" -Value "true"
Set-CsClientPolicy -Identity "<ClientPolicyName>" -PolicyEntry @{Add=$x}
