1. Can be operated from anywhere, no distance limitation; 2. No call charges for inquiry. the GSM Environment Alarm rejects the call from authorized number then return onsite temperature, humidity, and power voltage on the first 'ring'; 3. Multiple applications. (temperature, humidity, power status, solar panel, dc voltage); 4. Up to 10 authorized phone numbers, 5 can be used to receive call or SMS,and 5 can be used to call and SMS while alarm occurrence; 5. One Temperature & Humidity sensor input, measures temperatures from -40-80°C,0.5°C accuracy, Relative Humidity from 0-99RH%, accuracy is 3%; 6. External AC Power status monitoring, AC On/OFF will send SMS to authorized phone numbers; 7. Inbuilt MCU monitoring the DC input Voltage value, measure range is 9-24VDC, no need additional sensor to save cost; 8. Timer Report—Can setup every x hours automatically send its status/Value to the authorized numbers; 9. Support remotely read historic data via SMS; 10. Rechargeable Backup Battery inside can last 8hours; 11. Secure - Using caller ID and password for identification, unknown callers are ignored; 12. Programmable by SMS Commands or APPs with password protection; 13. Based on GSM Network, applied to many applications. My skype:Samchinese