You click the Ringtones and Sounds tab in the Lync - Options menu. Then, you click the Sound Settings button.
In the Sound window, you select the Windows Default (modified) option in the Sound Scheme list.
You try to change the sound file of an event in Program Events from the default file to none. For example, you click Second Incoming Call under Lync. Then, you select the (None) option in the Sounds list.
You save the changes. Then, you sign out of or exit Lync 2013.
Note When you sign out of or exit Lync 2013, if you open the Sound window from Control Panel or from the Speakers icon, you see the changes are saved.
You sign in to Lync 2013. Then, you open the Sound window.
In this scenario, the Windows Default (modified) option in the Sound Scheme list is selected. However, the audio file of the second incoming call is still selected as the default .wav file.
This issue occurs because Lync 2013 incorrectly resets the Null value of the .Current\(Default) and .Modified\(Default) registry subkeys to the implicit value during initialization. When you select the (None) option, the (Default) value of both the .Current and .Modified registry subkeys are set to Null in the following path: