VoIP in next-generation converged networks

Abstract

Introduction In telecommunications, there are many networks, such as the public switched telephone network (PSTN), signaling system 7 (SS7), the integrated services digital network (ISDN), the internet protocol network (IP network), the wireless local area network (WLAN), the global system for mobile communication (GSM), general packet radio service (GPRS), the universal mobile telecommunications system (UMTS), etc. ese telecommunications networks were designed to provide specific services, which are initially distinct and then converge into a single network [1]. Voice-over IP is a clear example of such convergent services [2]. To visualize this convergence, it is necessary to understand the historical development, which is summarized in the following events [3]: the introduction of automatic telephone exchange, the digitalization of telecommunications systems, the integration of circuit-switched technology and packet-switched technology (VoIP emergence), and the evolution of the mobile systems (1G, 2G, 3G, 4G, and beyond).