The Audio/Video Conferencing Server cannot communicate over SIP to the Microsoft Lync Server 2010 Front End Server. Microsoft ...

The Audio/Video Conferencing Server cannot communicate over SIP to the Microsoft Lync Server 2010 Front End Server.

Microsoft Lync Server 2010 Front Ends failing: %1
Cause: The Audio/Video Conferencing Server cannot communicate with the Microsoft Lync Server 2010 Front End Server over SIP due to network connectivity issues or unavailability of the Microsoft Lync Server 2010 Front End Server. This condition prevents setting up new conferencing sessions and is disruptive and potentially fatal for existing conferencing sessions. For additional information to troubleshoot the issue, please look at occurrences of the event AVMCU_E_SIP_CONNECTION_FAILURE (Event ID: 32077). This alert can result from a SIP Connection failure (Event ID 32077) or a TLS negotiation failure (Event Id 32078).
Resolution:
Please ensure network connectivity and availability of the Microsoft Lync Server 2010 Front End Server for the Audio-Video Conferencing Server to be able to function correctly. For additional information to troubleshoot the issue, please look at the events AVMCU_E_SIP_CONNECTION_FAILURE (Event ID: 32077) or AVMCU_E_TLS_FAILURE_EXCEPTION (Event ID: 32078).