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Thực hiện tiếng nói qua IP (P9)

CONCLUSIONS AND CHALLENGES1 The technologies and standards required to implement VoIP service are currently well established and mature. Many equipment manufacturers are presently marketing interoperable products—such as IP phones, call servers or managers, MGWs and SGs, and so on—to realize and manage the VoIP service. Advances in digital signal processing and networking software, hardware, and protocol technologies—as discussed in Chapters 2 and 3—have stimulated the development of plug-and-talk-based IP phones. These phones can support VoIP service over IP-based networks equipped with a call controller (CC) and MGW. . | Implementing Voice over IP. Bhumip Khasnabish Copyright 2003 John Wiley Sons Inc. ISBN 0-471-21666-6 9 CONCLUSIONS AND CHALLENGES1 The technologies and standards required to implement VoIP service are currently well established and mature. Many equipment manufacturers are presently marketing interoperable products such as IP phones call servers or managers MGWs and SGs and so on to realize and manage the VoIP service. Advances in digital signal processing and networking software hardware and protocol technologies as discussed in Chapters 2 and 3 have stimulated the development of plug-and-talk-based IP phones. These phones can support VoIP service over IP-based networks equipped with a call controller CC and MGW. As discussed in Chapter 6 IP phones can automatically register themselves to a DNS ENUM server once they are connected to an IP-based network. Furthermore these phones can derive electric power from the highly reliable Ethernet switches over those wires of the Ethernet cable a category 5 cable that are not being used for data services. The software and hardware configurations needed to deliver the subscribed services to the IP phones can be managed that is upgraded added or deleted by the subscribers themselves and the required configurations can be downloaded over the Web by the customers. Because of the openness and flexibility of IP-based call control and signaling many new and advanced add-on services can be developed integrated and marketed very quickly and cost-effectively. VoIP service can be implemented either in a standalone fashion or as a complement to existing PSTN-based telephone calling service. When VoIP service is implemented in a standalone fashion the following 1 The ideas and viewpoints presented here belong solely to Bhumip Khasnabish Massachusetts USA. 127 128 CONCLUSIONS AND CHALLENGES elements are needed IP phones various computer servers for DNS ENUM call control and signaling hosting of applications and features Ethernet switches .