The GSM-PRO2 module works on 2G/3G Network, allows you to control and monitor devices remotely from anywhere in the world. Product Features: 2/3G Communication GPS Functionality 2 Multi Function Analog/Digital Inputs 1 Digital Out 4 Expansion Units Available (8 multifunction analog inputs, 10 digital inputs, 4 analog outputs, 4 digital outputs) Smart phone App's available