The outgrowth of the wireless communications market has produced vast opportunities to enhance and improve the communications between individuals. Because of this growth, the need to optimize Radio Frequency (RF) spectral resources and provide ever-increasing services is essential. Therefore the TRS(Trunked Radio System) developed to efficiently utilizing the insufficient RF resources. The call setup request handled by control channel and then the call allocate to available traffic channel automatically. The many users can use less RF resources without interferences than general wireless site. And covered wide area by broadcasting method, a digital wireless system that uniquely combines digital mobile telephone and data technologies. Through all of these features and services, it utilized in public parts, telecommunication service provider, private parts. But the TRS transmission lines for a long distance sites is not economical, impossible to make redundance and difficult to manage each line. So, needs network with new concept to improve those issues. It's possible to fast transmission between iDEN core network and sites used by superhigh speed internet(LAN, WAN, MAN), satellite, wireless internet based on IP network which send E1 TDM data. Here looking for Motorola iDEN(Integrated Digital Enhanced Network) system and verified the system improve as more economical, effective, secure to applied IP tube system with TDM over IP technique. Build a thesis as follows. Chapter 2 introduces the TRS system and markets, the Chapter 3 describes the features and organization of the digital TRS, Chapter 4 presents the current network issues and how to improve the issues. And Chapter 5 summarized benefit of the IP-tube system as one of the enhanced network. Finally the Chapter 6 presents the results based on the analyzed-adjusted research data.