This is Small SIM800L GPRS GSM Module Micro SIM Card Core Board Quad-band TTL Serial Port, in this module two antennas have been included.

SIM800L GSM/GPRS module is a miniature GSM modem, which can be integrated into a great number of IoT projects. You can use this module to accomplish almost anything a normal cell phone can; SMS text messages, make or receive phone calls, connecting to the internet through GPRS, TCP/IP, and more! To top it off, the module supports quad-band GSM/GPRS network, meaning it works pretty much anywhere in the world

First is made of wire (which solders directly to NET pin on PCB) – very useful in narrow places. Second – PCB antenna – with double-sided tape and attached pigtail cable with IPX connector. This one has better performance and allows to put your module inside a metal case – as long the antenna is outside.

Caution: Use a resistor divider circuit before interfacing it with Arduino to avoid the damage to the module.

Features :

• TTL serial port for serial port, you can link directly to the micro-controller.
• Don’t need MAX232.
• Power module automatically boots, homing network.
• Onboard signal lights all the way.
• It flashes slowly when there is a signal, it flashes quickly when there is no signal.