If the phone number is busy, it will auto the next phone number, so that you will not miss anything important. [ Support dual network and work with Free APPs]: Support 2G/3G/4G sim card ( does not support 5G sim card) and 2., 4GHz WiFi ( does not support 5G WiFi). Smart Home Security Kit PGST Wireless Home Alarm System, Set Of 24 WiFi/4G Home Security Alarm System With Phone APP Alert (Door Sensor, Siren, Remote Control, Motion Detector) For Home DIY Home Alarm System Just fix the alarm host on the wall(screws are included), plug in the Micro C data cable and power it on. DIY YOUR HOME SECURITY SYSTEM TO ENJOY INTELLIGENT LIFE]: Multiple combination to pairing with additional PGST accessories,such as door window sensor/motion detector/SOS button/remote control/doorbell/outdoor siren.etc., easily extend your security system to fit your home layout Also, when the sensors are triggered, you will get real-time notification via APPs. Easy operate for the older and the children. When the sensors are triggered, the alarm system will issue more than 120db sound to scare off the intruders and will auto dial your phone number and send you a alarm message. // Work with Tuya and Smart Life APP, you can operate anywhere on APPs. Package includes 1* alarm host; 4* motion detectors; 8* door window sensor; 3* remote controls; 3* RFID card; 1* alarm siren., [ 4., 3 inch touchscreen ]: 4., 3 inch IPS capacitive touch screen, simple style, responsive and enhanced user experience. Aazon.co : PGST Security Alar Syste 99 3 Zone Auto Dial WiFi GS/4G [ Easy to install ]: No professional knowledge needed, you can install it in minutes. Diy Home Alarm Systems | OnePronic Support expansion of up to 200 accessories, such and motion detector, door window sensor and other accessories which can work with Tuya and Smart Life APP.