Radio paging

A pager (also known as a beeper) is a wireless telecommunications device that receives and displays alphanumeric messages and/or receives and announces voice messages. One-way pagers can only receive messages, while response pagers and two-way pagers can also acknowledge, reply to, and originate messages using an internal transmitter. Pagers operate as part of a paging system which includes one or more fixed transmitters (or in the case of response pagers and two-way pagers, one or more base stations), as well as a number of pagers carried by mobile users. These systems can range from a restaurant system with a single low-power transmitter, to a nationwide system with thousands of high-power base stations.

In the 2000s, the widespread availability of cellphones and smartphones has greatly diminished the pager industry. Nevertheless, pagers continue to be used by some emergency services and public safety personnel, because modern pager systems' coverage overlap, combined with use of satellite communications, can make paging systems more reliable than terrestrial based cellular networks in some cases, including during natural and man-made disaster. This resilience has led public safety agencies to adopt pagers over cellular and other commercial services for critical messaging.

The first telephone pager system was patented in 1949 by Alfred J. Gross.

One of the first practical paging services was launched in 1950 for physicians in the New York City area. Physicians paid $12 per month for the service and carried a 200-gram (7 oz) pager that would receive phone messages within 40 kilometres (25 mi) of a single transmitter tower. The system was manufactured by the Reevesound Company and operated by Telanswerphone. In 1960, John Francis Mitchell combined elements of Motorola's walkie-talkie and automobile radio technologies to create the first transistorized pager, and from that time, paging technology continued to advance, and pager adoption still continues to expand, as of July 2016.

In 1962 the Bell System—the U.S. telephone monopoly colloquially known as "Ma Bell"—presented its Bellboy radio paging system at the Seattle World's Fair. Bellboy was the first commercial system for personal paging. It also marked one of the first consumer applications of the transistor (invented by Bell Labs in 1947), for which three Bell Labs inventors received a Nobel Prize in Physics in 1956. Solid-state circuitry enabled the Bellboy pager, about the size of a small TV remote device, to fit into a customer's pocket or purse, quite a feat at that time. The Bellboy was a terminal that notified the user when someone was trying to call them. When the person received an audible signal (a buzz) on the pager, he found a telephone and called the service centre, which informed him of the caller's message. Bell System Bellboy radio pagers each used three reed receiver relays, each relay tuned to one of 33 different frequencies, selectively ringing a particular customer when all three relays were activated at the same time—a precursor of DTMF. The ReFLEX protocol was developed in the mid 1990s.

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