填空题 Voice Over IP
VoIP or Voice over IP has been steadily evolving over about a decade. VoIP is
generally considered as a subset of IP telephony -- a collection of technologies
41 that, being broadly described, encompass the convergence of voice, video, and
42 data on a public or private IP network. VoIP technology has been adopted by
43 practically all the major telecom carriers and service providers, including AT&T,
44 Level 3, and Sprint, who will have been offering VoIP as an option with their
45 respective virtual private network (VPN) services for several years, with
46 providing quality of service guarantees for VoIP calls. The basic VoIP's primary
47 benefit is that it saves up money. By using VoIP equipment on site , businesses
48 get to bypass the traditional phone network to dramatically cut down phone costs
49 between branch offices and the other locations. Savings of 70% to 90% for
50 international calls are not uncommon, while many companies can not enjoy a
51 20% to 30% reduction in costs for domestic long distance. The basic VoIP which
52 indicates a transformation from a circuit-switched communications infrastructure to one based on IP data packets in our communications technology industry.