A pager is a wireless telecommunications device that receives and displays numeric or text messages, 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.
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 6 oz (200 g) pager that would receive phone messages within 25 mi (40 km) 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 continued to expand, until the early 1990s. However, by the mid-1990s, as cellular technologies became cheaper and more widely available, advanced services began to displace paging as a commercial product. Today, pagers exist largely as niche products, finding preferential use in applications such as hospitals, public safety, and retail locations where their simplicity, high reliability, and low cost represent significant advantages.
Pagers themselves vary from very cheap and simple beepers, to more complex personal communications equipment, falling into eight main categories:
Beepers or Tone-only Pagers are the simplest form of paging. They were named beepers because they originally made a beeping noise, but current pagers in this category use other forms of alert as well. Some use audio signals, others light up and some vibrate, often used in combination. The majority of restaurant pagers fall into this category.
Voice/Tone pagers provide the ability to listen to a recorded voice message when an alert is received.
Numeric Pagers contain a numeric LCD display capable of displaying the calling phone number or other numeric information generally up to 10 digits. The display can also convey pager codes, a set of number codes corresponding to mutually understood pre-defined messages.
Alphanumeric Pagers contain a more sophisticated LCD capable of displaying text and icons. These devices receive text messages, often through email or direct connection to the paging system.
Response Pagers are alphanumeric pagers equipped with built-in transmitters, with the ability to acknowledge/confirm messages. They also allow the user to reply to messages by way of a multiple-choice response list, and to initiate canned messages from pre-programmed address and message lists. These devices are sometimes called "1.5-way pagers" or "1.7-way pagers" depending on capabilities.
Two-way Pagers are response pagers with built-in QWERTY keyboards. These pagers allow the user reply to messages, originate messages, and forward messages using free-form text as well as canned responses.
One-way Modems are controllers with integrated paging receivers, which are capable of taking local action based on messages and data they receive.
Two-way Modems have capabilities similar to one-way modems, and can also confirm messages and transmit their own messages and data.