No monthly fees and contracts with security companies,Just pay the cell phone operation service provider; Put-in a GSM SIM card (This alarm do not including GSM sim card) to call/send alert message, you can choose one of two ways or use all of them. The whole system complete with fully programmable main unit and wireless sensors. Before using, please kindly read user's manual | Network Support: The alarm panel built-in GSM Module, it support GSM SIM card, T-Mobile sim card can work with our system (This alarm do not including GSM sim card). When the sensor is triggered, the alarm panel will make an call or send alert message to the alert phone number you set before. The GSM (only) frequency is 850/900/1800/1900MHZ, which can be applied in all over the world; In GSM status, 6 groups calling alert phone number and 2 groups help SMS number you can set | Loud Emergency Alarm and Easy to Get Help: Children and seniors at home in emergency, press the emergency alarm button of the remote controller, which will trigger all alarms and send emergency calls and messages to other families, so they can get help in time. Support 6 groups preset alarm phone number, if alarm occurs, the host will dial preset number automatically and 10 seconds help voice recording | Defense Zone Support: Allow up to 99 wireless defense zones and 7 wired zones, 5 groups of scheduled arm/disarmed function; 2 wired siren for different size houses as you need; DIY home security, tool-free setup and assembling, plug and play installation | With 10 second manual recording function to leave messages