Module models: SIM800L (latest module, performance than SIM900 / M590)
Operating voltage: 3.7 ~ 4.2V (maximum current is 1A)
High quality: the serial interface is a TTL serial interface which can be directly connected to the microcontroller. MAX232 is not required
With signal light: the on-board signal is fully illuminated. Flashes slowly when there is a signal, flashes quickly when there is no signal.
FUNCTION - The ignition of the module starts automatically and automatically finds the network