Supply pins: VBTA: voltage :3.5-4 .5 v (recommended 4V) Current: 1A, we must pay attention to: the voltage and current must satisfy this condition, the module must not use! The 5V directly connected modules are burned.
The, communications pin: RX TX GND recommended 3.3V MCU to use, the 5V MCU you want to add level conversion module, then the computer use usb to TTL or serial cable +3.3 VMAX3232 communication.
4, the boot pin: S-POWERKEY to high 1S to open the module. Module is turned on the lamp and probably 1S flashes once when the card is connected to the network, the module is probably 3s blink once. 5, LED: power indicator, the module signal indication, serial communication instructions
6, clamshell SIM card connector, with EMI immunity circuit.
7, core board with fixing holes and the auxiliary fixed pin, can be embedded directly into your production which, convenient, stable, fast.