 use some of the capacity to transmit voice communications as well. Some organizations do this and others are experimenting with it as a means of cost reduction. There are many quality of service considerations and associ- ated start up costs for using a data communications network to transmit voice. Cellular Telephone Service Most telecommunications service providers now sell cellu- lar telephone service. While cellular telephone calls often use the existing network of the telecommunications service provider for some portion of the call (may be called land lines or wire based services), the initial connection to the network from the cell phone is made without a physical connection based upon a cable. The Telecom Handbook 281 UNDERSTANDING THE INDUSTRY Cellular service providers erect transmission towers at dif- ferent points within a geographic area to enable the cellular transmissions. The ISP or Internet service provider provides access for or- ganizations to reach the Internet. They may also provide a group of Internet related services such as the hosting of an organization's e-mail or web site. The ISP is reached either by the computer dialing into a certain telephone number or over a permanent connection provided by the ISP using the cable of a local tele- phone company. Cable Television Companies Cable Television companies are making some inroads into providing services traditionally offered by local telephone companies, such as a local telephone lines for placing and re- ceiving calls and data communications including access to the Internet. While the cable TV company has cable running into most homes, it still needs to invest in considerable amounts of equipment to turn its system into one that can be used for telephone service and Internet access. Since cable TV does have much more of a presence in homes than in businesses, cable TV companies are selling telecommunications services primarily to residential users. Pagers and Messaging Devices Some wireless companies also sell the traditional beepers and 