Voice-over-IP (VoIP) Technology

Voice-over-IP
(VoIP)
Technology

As we have seen in previous chapters, the development of wireless technology
involves a migration from the circuit-switched solutions of firstgeneration
(1G) and second-generation (2G) networks towards a completely
packet-switched configuration for both voice and data. Although a number
of packet-switching solutions could be leveraged, such as Asynchronous
Transfer Mode (ATM) or Frame Relay, the ultimate goal is to use the Internet
Protocol (IP). In fact, if we examine the migration from Global System
for Mobile communications (GSM) to the Universal Mobile Telecommunications
Service (UMTS) Release 5, we see the use of Frame Relay (the General
Packet Radio Service [GPRS] Gb interface), followed by ATM, followed by IP.
Although the IP transport of data is well understood, the IP transport of
voice is a relatively recent development. Given that Voice over IP (VoIP) will
be used in third-generation (3G) networks, it is appropriate that we describe
the solutions that make VoIP possible. Therefore, this chapter is devoted to
a brief overview of VoIP technology. It should be noted, however, that the
explanations provided in this chapter are at a relatively high level and are
certainly not detailed enough to provide a complete understanding of all
aspects of VoIP. This is, after all, a book about 3G wireless.