This object indicates the operational state of the session group. The possible operational states are as follows: 'idle': This is the initial state. 'oos' : Out of service state. when a session group has been created the state of the session group becomes 'oos' or when all sessions belonging to this group are deleted, session group state becomes 'oos' 'is': In service state. After at least one session has been added to the group, socket has been successfully set up and the session has sent a START message to MGC the group state changes to 'is'. 'unknown': This is the state other than the above states.