di- technology. aling plans and special PIN numbers, or requires signifi- cant time to complete a call, or has constant call drops, New services then the IP gateway will only be used by a limited client Another advantage IP telephony has over the PSTN is base. VoIP is not a new network, but a new application on that it enables the creation of a new class of service that CHAPTER 3.2 Network infrastructure Mainframe Figure 3.2-7 Integrated Voice and Data over Frame Relay network. combines the best characteristics of real-time voice premise equipment (CPE), enterprise LANs, and In- communications and data processing, such as web-en- ternet connections. IP telephony applications can be abled call centers, collaborative whiteboarding, multi- implemented through dedicated gateways that in turn media, telecommuting, and distance learning. This can be based on open standards platforms for reliability combination of human interaction and the power and and scalability. efficiency of computers is opening up an entirely new world of communications. Market size There is a wide range of numbers describing the current Progressive deployment size of the IP telephony market and the growth of the The final advantage of VoIP is that it is additive to market over the next three to five years. While the spe- today's communications networks. IP telephony can be cific projections vary, even the most conservative analysts used in conjunction with existing PSTN switches, are predicting phenomenal growth. The numbers are leased and dial-up lines, PBXs and other customer summarized in Figure 3.2-8. Applications Carrier-class solutions Enterprise solutions Core enabling technology Figure 3.2-8 IP telephony growth. Network infrastructure CHAPTER 3.2 VoIP is very complex because it involves components Table 3.2-5 of both the data and the voice world. VoIP is a revolu- tionary solution as, historically, data and voice worlds Media gateway controller Coordinates setup, handling, and have used two different networks, two different support termin