The current state of ccmCTIDeviceTable. The initial value of
this object is 0 and it will be incremented every time when
there is a change (addition/deletion/modification) to the
ccmCTIDeviceTable. This value and ccmCallManagerStartTime
should be used together to find if the table has changed or
not. When the call manager is restarted, this will be reset
to 0.