all servers, to replace the use of traditional circuit switches, allowing the support of voice communications over IP backbones rather than the circuit- switched PSTN. From the standpoint of an enterprise network, this can also involve the use of IP PBXs at the customer premises or a service provider making IP centrex available to the enterprise, as well as integrated access devices (IADs) that combine voice and data traffic before presenting it to the external network. Convergence in Applications In the realm of applications, convergence refers to the integration of voice, data, and video at the desktop or in servers. Examples of this include integrated messag- ing, instant messaging, presence management, real-time rich-media e-learning and Chapter 10 Next-Generation Networks training products, multimedia sales presentations, and a variety of interactive pro- grams, such as videogames. A host of such applications are unique and specific to various vertical industries, including health care, education, entertainment, gov- ernment, and warfare. Arguments for Convergence One of the primary arguments for convergence has to do with cost reductions. As discussed earlier, packet switching is a more efficient approach than circuit switch- ing for carrying conversations, particularly those that may be bursty in nature. With the continuing reduction in the cost of electronics, with the growth in traffic levels, and with the emergence of an increasing number of competitors, the price of delivering a packet on the backbone has been dropping by about 45% to 50% per year. Of course, we're now approaching a stabilizing point; nevertheless, packet switching has continually become more cost-efficient than the traditional circuit- switched network, or PSTN. Another cost-reduction argument for convergence is in support of VoIP, and the major savings here occur through bypassing normal toll operations. Of course, this is most dramatic on international calls. There are some other arguments for convergence as well. One is that you ge