This variable represents the source from where the system shutdown was performed. Possible values are: DTE-Port - if the system shutdown is performed using the DTE, AUX-Button - if the system shutdown is performed using the AUX button (available only for IP500v2), Phone <user name> - if the system shutdown is performed from a phone, Manager <security user name> - if the system shutdown is performed from Manager, SSA <security user name> - if the system shutdown is performed from SSA.