Lync Server 2010, Response Group Service declined the incoming call because the system is running on a high load. System ...

Lync Server 2010, Response Group Service declined the incoming call because the system is running on a high load.

System is set to decline incoming calls when the number of active calls has reached %1. Accepting calls will resume once the number of active calls will decrease.
Cause: The server is under high load.
Resolution:
Consider restarting the service.