This book shows how to build a "INFelecPHY GPS Unit" (IEP-GPS) tracking system for fleet management that is based on 3G and GPRS modules. This model should provide reliability since it deals with several protocols: 1) HTTP and HTTPS to navigate, download and upload in real time the information to a web server, 2) FTTP and FTTPS to handle in a non-real time the files to the web application, and 3) SMTP and POP3 to send and receive email directly from the unit in case of any alert. Similar to a mobile device, but without screen for display, it is multifunctional because it links to a GPRS module, a camera, a speaker, headphone, a keypad and screen.