CHAPTE R 2 Basics of Wireless Networks Looking at the IP Multimedia Subsystem (IMS) in isolation, it is difficult to find anything wireless about it. So why are wireless network concepts essential? The answer is that even though we see IMS as a blueprint for converged networks, IMS originated as and will continue to remain an integral part of the wireless network. Two prominent standards define Wireless Telecom Networks. The International Telecommunication Union (ITU) and European Telecommunications Standards Institute (ETSI) standards have laid out the Global System for Mobile (GSM), General Packet Radio Service (GPRS), and Universal Mobile Telecommunication System (UMTS) networks. The American National Standards Institute (ANSI) standards have defined the