This document provides an overview of 3G mobile radio technology. It begins with a brief history of cellular wireless standards from 1G to 2G, including AMPS, TDMA, CDMA, GSM and their evolution. It then discusses evolving network architectures, focusing on the migration from GSM and ANSI-41 networks to all-IP networks. The document also outlines evolving services, applications and business models for 3G. Key topics covered include 3G standards like UMTS, CDMA2000 and TD-SCDMA, as well as spectrum bands and the challenges of global roaming.