SLS transitions to the Teardown state whenever the following events occur:
The Branch Gateway administrator uses the set sls disable command from the Branch Gateway CLI or manual MIB browser using the SNMP read/write attribute avSurvAdminState.
The Branch Gateway closes the SLS socket after maintenance determines that it has completed an H.248 registration with the primary MGC.
SLS determines that it needs to unregister with the Branch Gateway due to internal error conditions.
