Paging (telecommunications)
From Wikipedia, the free encyclopedia
There are two related meanings to the word Paging in telecommunications. The first is the general act of broadcasting a message through a network in order to contact a remote radio system. This is used in cellular networks, for example, and is covered in detail in that entry.
Paging in the other, more widely known sense means the use of a paging device through a paging service. The paging device is a telecommunications device that alerts the user via a sensory message, such as an audible beep, flashing, vibration, or an updated display. The paging service is a service provided by the teleoperator that can be used to send one-way messages to the subscriber of the paging service.
Paging was one of the earliest forms of digital wireless communications and used digital technology long before cellular phones went digital. Paging remains one of the most reliable forms of messaging around and is still used largely by emergency services and hospitals who need reliable realtime messaging and the ability to send broadcast messages to a large number of people simultaneously. Cellular SMS, on the other hand (often compared to paging), is less reliable and far from real time with significant delays common between sending a text message and its receipt.
First introduced in the USA in the 1960s, paging networks reached their height of popularity in the 1980s in most places. There is a common perception that paging is obsolete, but there are well over 6 million subscribers in the USA alone and new networks are being put up in 2006 in Europe and Australia among other countries. Though no longer commonly used by consumers, paging remains the most prevalent means of dispatch and messaging for emergency services, hospitals and for on site commercial messaging in factories and campuses. Despite the reduction in popularity, the lower radio frequencies used by paging systems, the ability to use higher RF power levels, and no need to engineer coverage to avoid interference between mobile phone "cells" leads to superior coverage versus cell phone SMS systems.
The most common protocols used in paging are Flex and pocsag. Both have their advantages and disadvantages. Flex is a proprietary protocol owned by Motorola, but pocsag is an open standard developed originally by the British Post Office. Other less common protocols are ERMES (a European open standard) and Golay an older Motorola protocol.
