Cellphones

Cell phones are mobile hand-held devices that can be used to contact people next door or in the next country.

Each cell-phone service provider has a network of bases, or cell sites. These sites have antennas on towers, poles, or buildings to receive radio waves. When a call is made, voice and data are sent to and received at the nearest cell site (about ½ to 10 miles away). From there, they go to a switching site and then to the phone being called (if it is on the same network) or to the public telephone network, which connects to other service providers’ networks. As phone users move about, the phone automatically connects to the nearest cell site.

Radio-telephones on ships, aircraft, and military vehicles in the 1940s were the first type of mobile phone. In the United States, the first cellular system was created in 1977; it was tested in 1978, in Chicago, and in 1981, in the Washington-Baltimore area. In 1982, the Federal Communications Commission let commercial service providers set up businesses.

Until the late 1980s, cell phones could only be used in certain places and were so expensive and so big that they were usually installed in cars for business use. When new technology led to smaller (and smaller) phones that could be used across different service-providers’ networks and countries, the number of users increased and the price dropped. Today, countless adults, teenagers, and even children use them. India and China have the highest growth in numbers of cell-phone users.

Cell phones ringing at unsuitable times and people talking too loudly on them have caused libraries, theatres, and churches, for example, to ban their use. People who talk on them while driving are more likely to get into an accident. The phones’ poor security systems make it possible to listen in on other people’s conversations. Finally, some claim that using cell phones for long periods of time may cause cancer or genetic damage, but this has not been proven.