Lync Server 2010, Response Group Service declined the incoming call because the system is running low on memory. System is ...

Lync Server 2010, Response Group Service declined the incoming call because the system is running low on memory.

System is set to decline incoming calls when the percentage of private bytes in use is greater than %1 percent.

Currently %2 percent of privates bytes are in use and the call from %3 was declined.
Cause: The server is under high load or it is facing a memory leak.
Resolution:
Consider restarting the service.