Generic Access Network (GAN) is a telecommunication system which extends mobile services voice, data and IP Multimedia Subsystem/Session Initiation Protocol (IMS/SIP) applications over IP access networks.This report will attempt to discuss the details of the GAN, its evolution, its services, architecture, and other implications. The Generic Access Network (GAN) is an evolving wireless communications system in which mobile phone sets function seamlessly between local area networks (LANs) and wide-area networks (WANs). Using GAN technology, a cell phone subscriber can communicate by voice, data and multimedia. As GAN technology is implemented, cellular telephone subscribers can expect improved coverage, the ability to use a single phone set for all their voice communications and perhaps cheaper rates with a single bill for Internet and voice communications.