Radio-paging code No. 1

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Radio-paging code No. 1 (usually and hereafter called POCSAG) is an asynchronous protocol used to transmit data to pagers. Its usual designation is an acronym of the Post Office Code Standardisation Advisory Group, the name of the group that developed the code under the chairmanship of the British Post Office that used to operate most telecommunications in Britain before privatization.

Before the development and adoption of the POCSAG code, pagers used one of several codes such as binary Golay code.

In the 1990s new paging codes were developed that offered higher data transmission rates and other advanced features such as European and network roaming.

The POCSAG code is generally transmitted at one of three data rates; 512, 1200 or 2400 bits per second.

With Super-POCSAG, 1200 bits per second or 2400 bits per second transmission rates are possible. Super-POCSAG has mostly displaced the POCSAG in the developed world but the transition is still in progress.