A GSM modem is a wireless modem that works with a GSM wireless network. GSM stands for Global System for Mobile communications, this architecture is used for mobile communication in most of the countries in the world. A wireless modem acts basically like the traditional dial-up modem, the main difference is that a dial-up modem sends and receives data through a fixed telephone line while a wireless modem sends and receives data through radio waves. Besides the dial-up connection, GSM modem can also be used for sending and receiving SMS which is also one of the key features of GSM modem. A GSM modem can be used in many applications including: Remote System Monitoring, Remote Controlling System, Prepaid Electricity, Home Alarm System, Home Automation, Data loggers, Vehicle tracking, etc. In this article we are going to learn the basics commands to control a GSM modem with a PIC Microcontroller, including sending and receiving an SMS using MikroC Pro for PIC.