Module SIM900A GSM GPRS Shield Serial Modem for Arduino

This module advantages:
Serial circuit: The TVS and bead protection devices to protect the board so that the board will not be a surge, high voltage damage.
SIM card circuit: increase SMF05C chip electrostatic discharge.
The antenna circuit: to ensure short and straight, so as to ensure that the signal strength.
PCB show: silk mark each interface, convenient secondary development, full compliance with SIM900A hardware design manual design.
A 5V power supply Interface: We do protection, even reversed, it will not burn the board. Early computer debugging USB-powered computer can ; for a long time to transfer data consumption greater than 1A DC we recommend.
All the way TTL interface: Supports 3.3V and 5V MCU MCU. That kind of support 5V microcontroller 51 and STM32 microcontroller.
Two Antenna Interface: SMA antenna interface, IPX MINI antenna interface (the default is not welding).
All the way to 232-level interface: that you can directly connect the module to the computer via a RS 232 — USB serial cable. You can also USB – TTL connected to the computer, based on individual parts circumstances.