 networks with their signaling, service nodes, etc. (an equivalent router costs an order of magnitude less than a PBX or a Class 5 central office switch interconnecting the same bandwidth.) The problems facing VoIP are latency and quality of ser- vice. The latency problem arises when a packet has to "hop" between multiple routers. For example, if each router takes 30 milliseconds to route a packet, the delays build up quickly and soon an echo or "talkover" results. Quality of service is- sues arise because current IP technology used on the Internet cannot prioritize voice over a video being downloaded, for example. Telecommunications carriers implementing VoIP are using proprietary schemes or emerging standards not yet de- ployed on the Internet. 144 The Telecom Handbook CHAPTER 7 Latency Latency is a fancy term for waiting time or time de- lay. It refers to the time it takes to get information through a network. Real-time interactive applications such as voice (telephone calls) and desktop video, are sensitive to ac- cumulated delay, which is called latency. - Compliments of Newton's Telecom Dictionary Communications Servers As part of the trend towards convergence, there is a develop- ing group of telephone systems, from different manufacturers, sometimes called communications servers, suggesting that voice communications is becoming simply another function of the com- puter network. As with any developing technology, different systems are be- ing put together in different ways. Most of the communications servers have separate desktop telephones (most still proprietary and can only be used with one system). Some provide the tele- phone capabilities (transfer, conference, etc.) right on the computer screen, using the computer mouse to control telephone functions. There has yet to be a wide acceptance of using the computer to totally replace the conventional telephone, except in the large incoming call center. Larger versions of communications servers are being deployed by telecommunications service providers to 