SIM800L GPRS GSM Module
Chip: SIM800L
Operating Voltage: 3.7-4.2V
Module Dimensions: 2.5cm x 2.3cm
Serial Communication: TTL serial port, directly compatible with microcontrollers (no need for MAX232)
Power Management: Automatic boot and network connection upon powering
Signal Indicator:
Flashes slowly when connected to the network.
Flashes rapidly when no signal is detected.