A GSM modem is a wireless modem that works with a GSM wireless network. GSM stands for Global System for Mobile communications, this architecture is used for mobile communication in most of the countries in the world. Features:– Chip: SIM800L– Voltage: 3.7-4.2V– Support networks: Global quad-band network– Module size: 2.5cm x 2.3cm– TTL serial port for serial port, you can link directly to the microcontroller. No need MAX232– Power module automatically boot, homing network– Onboard signal lights all the way. It flashes slowly when there is a signal, it flashes quickly when there is no signal Hardware Design ManualAT Commands Manual Package Included: 1 X SIM800L GPRS/GSM Module1 X GSM Antenna1 X Pin header set Applications Remote System Monitoring: In a remote system monitoring application, a Microcontroller for example could be used to constantly monitor the status of a remote sensors, let say temperature or moisture sensors. If a certain condition is reached, the program will send an SMS to notify the situation, if these sensors are installed in a farm for example, the farmer could be notified of any situation happening in the farm about heat, moisture, drought, etc. Home Alarm System: When a motion sensor detects a movement of an intruder, an SMS will be sent to a predefined number which could be you or your security reaction company and a siren or any other sound device could be triggered in the process as well. Remote Controlling System: A mobile phone can be used to Send an SMS to switch ON/OFF remote devices. You could control your entire home devices, switching ON/OFF lights, fans, pool motor, garage motor and so on with just a simple SMS from a distance. Security Access Control: A security access can be implemented at apartments or housing complexes. A security guard could inform by intercom a resident if he/she has a visitor at the main gate. with a replied SMS, the resident could open remotely the gate for his/her visitor. Vehicle tracking: A GSM/GPRS module together with a GPS module can be used to create a real time vehicle tracking device. An SMS could also be sent to notify that the car has entered a restricted area, notify about the level of remaining fuel in the car etc. If the vehicle is stolen not only the system can indicate the location of the vehicle but an SMS could also be sent to switch OFF the engine. SMS Gateway: To send and receive SMS for advertisements. Pre-paid Electricity: The customer can recharge pre-paid electricity by sending an SMS with a recharge coupon to a pre-paid electricity recharge server. Specifications Chip: SIM800L Voltage: 3.7-4.2V, please do not over 5V, or it will be burned. TTL serial port for serial port, you can link directly to the microcontroller Support networks: Global quad-band network Module size: 2.5cm x 2.3cm