SIM CARD: Desires a devoted info sim to the SMS messages,put it in the rear slot of the key alarm box.can insert 6 teams preset alarm telephone number and three teams sms contact number Major highlights WARM PROMPT: The batteries are items. In case the batteries are useless,pls get it https://www.firesense.co.uk/type/conventional-fire-system/conventional-fire-alarm-control-panels/