This alarm system support different alarm channels(APP Push / SMS / Voice monitoring / intrannet center Alarm to meet diiferent needs).Wifi way:(It just support 2.4g wifi, not 5g). It will push alarm notification via free app when it is triggered. GSM Way: Insert a SIM card into the alarm system and save your phone number on it,then it will send message or call your cell phone when alarm alerts. You can remote control home sensors setting, easily to remote arm/disarm all sensors, or set up message and call real-time push notifications setting and view all sensors’ status from APP.Notes for sim card a.SIM card must support GSM (key point) b. The SIM card cannot be encrypted with PIN code (if there is, it can be used to unlock the PIN code on the phone) c. The device has IMEI code, it will automatically activate and identify the SIM card after plug in.