... . Automation System, M2M;19. GSM Access Control System, GSM Gate Opener, etc. Mainly Features of the GSM SMS Controller-Alarm ... speaker; Supports armed, disarmed, inquiry status, switch on or off relay output by SMS Commands; Password protected, prevents unauthorized user ... Backup rechargeable battery inside, can work for 24hours when power off; Can be operated from anywhere, no distance limit; Based ...