You select the Keep Windows settings, personal files and applications option when you upgrade a computer from Windows 7 to Windows 8.
You install the Microsoft Lync Windows Store app.
You use the Lync Windows Store app to start a call though a non-corporate WLAN connection (such as a home Wi-Fi connection or an open Wi-Fi connection).
In this scenario, the call fails.
This issue occurs because restrictive WLANApiPermissions settings are set when you upgrade to Windows 8 and select the Keep Windows settings, personal files and applications option. These settings do not allow the Lync Windows Store app media flow.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows