SIM800L GPRS GSM Module Core Board Quad-band TTL Serial Port with the antenna
1. TTL serial port for serial port, you can link directly to the micro-controller. 2. Don't need MAX232. 3. Power module automatically boots, homing network. 4. Onboard signal lights all the way. 5. It flashes slowly when there is a signal, it flashes quickly when there is no signal.