... -240V 5.433mhz, 315mhz Functions & Features of the GSM Alarm System :1.Touch keypad; Big LCD displays, NO EXTERNAL GSM ANTENNA ... setting.5.Preset 5 phone/SMS alarm number in the system, 1 extra phone alarm number for CID CMS, 1 extra ... with Contact ID protocol(alarm information, status information, AC power off and recover, Low voltage, test)8.Support wireless “ding-dong” doorbell , user ...