1Can be controlled anywhere, not limited by distance. 2There is no charge for each request. The GSM alarm system rejects calls from authorized numbers and then returns to temperature, humidity. 3Up to 10 authorized phone numbers, 5 can be used to answer calls or text messages, and 5 can be used to make calls and text messages when an alarm occurs. 4Externally monitor the status of the AC power, the AC current on/off will send a text message to the authorized phone number. 5Timer report - can be configured to automatically send its status/value to the authorized number every x hours.Features: 1. Can be controlled anywhere, not limited by distance. 2. There is no charge for each request. The GSM alarm system rejects calls from authorized numbers and then returns to temperature, humidity. 3. Multiple applications. (temperature, humidity, power state, solar panel, DC voltage). 4. Up to 10 authorized phone numbers, 5 can be used to answer calls or text messages, and 5 can be used to make calls and text messages when an alarm occurs. 5. Based on the GSM network, it is suitable for many applications. 6. Externally monitor the status of the AC power, the AC current on/off will send a text message to the authorized phone number. 7. Built-in MCU DC input voltage monitoring, measuring range is 9-24 VDC, no additional sensors, saving cost. 8. Timer report - can be configured to automatically send its status/value to the authorized number every x hours. 9. Support remote reading of historical data via SMS. 10. The rechargeable battery can last for 8 hours. 11. Security - Ignore unknown callers when using caller ID and password for identification. 12. Program using SMS commands or password protected applications.Specification: Power supply: 9-24V DC, reference voltage: 12V DC, 1A Working current: 30-50MA (12V input) GSM frequency: 850/900/1800/1900Mhz SIM card: 3V SIM card Built-in battery: 900mAH, working 8 hours Relative temperature: -40-80 C Relative humidity: 0-99% (no condensation) Temperature and Humidity Probe Type: AM2301 Temperature measurement range: -40-80 C (0.5C error) Humidity measurement range: 0-99RH% (3% error) Package List: 1 * Temperature Controller 1 * Power Adapter 1 * Terminal 1 * English Manual Note:AM2301 temperature and humidity sensor is not included in this product, please buy it by yourself.