Article ID: 2913477 - View products that this article applies to.
Consider the following scenario:
This issue occurs because Lync for Mac 2011 tries to reconnect to the front-end server by using the TCP port that does not support external access.
To resolve this issue, install the following cumulative update:
(http://support.microsoft.com/kb/2909662/ )Description of the Microsoft Lync for Mac 2011 14.0.7 update