... screen GSM Alarm,wireless alarm,home alarm,GSM home alarm,wireless alarm,home alarm system,mms home alarm,home securityDescription and Main functionsFeatures: ... if in emergencies. 17. External power failure alarm.Switch to Backup rechargeable battery when the power is failure ... Two way communication function. 19.With Main unit with tamper switch.20.Support language: Chinese, English, Spainish, French, ...