ate connec- tion. ISDN provides a reliable 64/128-Kbps connection end to end, which is much more than that available for subscribers using a voice-band modem over an ordinary analog telephone circuit. Users may connect up to eight terminals to a network terminal and two of them may be in use at the same time. The advantages of ISDN over the analog telephone service are a higher data rate and the availability of two con- nections at the same time. ISDN technology has been available for some time but its usage has been low because of high tariffs in the past. Today operators offer attractive tariffs and the increased demand of better Internet connec- tions in particular has increased ISDN's popularity to some extent. On the other hand, higher rate access technologies, such as xDSL and cable modems, provide better performance and they have cut the growth of ISDN. The Telecommunications Network: An Overview However, the existing low-cost ISDN technology makes it feasible for net- work operators to provide ISDN connections sometimes at a lower cost than two conventional analog telephone connections. 2.10.1.8 Radio and Television Networks Radio and television networks are usually unidirectional radio distribution networks for mass communications. Traditionally, the operators of these net- works have not provided dial-up bidirectional telecommunications services. Access to these networks is currently available in urban areas via cable TV networks built by cable TV operators. These operators have not been allowed to provide other telecommunications services and their wideband cable net- work to homes has not supported bidirectional communication. As the deregulation of the telecommunications business has proceeded, these opera- tors have become active in providing other telecommunications services as well, especially fixed telephone service and high-data-rate Internet access. To provide interactive services, the cable TV networks need to be upgraded with the technologies that allow subscribers not only to receive TV and 