Historical Background of Mobile and Cellular Services

Prior to the first deployment of analog cellular car telephones in 1984, users who wanted to place telephone calls from their cars used mobile non-cellular telephone networks that had connections to the public switched network. The first mobile telephone system was started in 1946 in St. Louis, Missouri. Costs for car telephones were high, between $2000 to $2500, and capacity was limited. The local telephone company in each city operated one transmitter and receiver for the entire area. Thus, the entire area covered by the one transmitter shared the same channels. This meant that only a limited number (25 to 35) of simultaneous calls could be placed on each city's mobile system. In addition to limited capacity, the quality of service was spotty with considerable static and breaking up of calls.

Mobile radio service was more widespread than mobile telephone service prior to the mid-1980s. Mobile radio is a “closed” service without connections to the public switched network. Mobile radio operators can only reach people on their closed network. For example, users on one taxicab service's system cannot call users on another cab's system. Police departments were early pioneers of car radios. The Detroit police department used mobile radio service in 1921. In the 1930s, mobile radio use spread to other public safety agencies such as fire departments. Mobile radio systems are now used for aviation, trucking, taxis and marine applications.

Mobile radio is half-duplex: Calls are two-way but only one user at a time can transmit. For example, when one person is done speaking, he uses a convention such as “over and out” to let the other person know he is finished talking. People using mobile radio push a button to talk.