Assume that you have multiple conversation tabs opened in Microsoft Skype for Business 2015 (Lync 2013), and you use the Windows hotkey (Windows + F4) to mute or unmute the current audio. In this situation, unread prompts on previous audio conversation windows are triggered. Additionally, you will see a generic message like "call is already ended". Even if you dismiss the prompt message, it will repeat when you use the hotkey.
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