![]() These offer waiting patients the opportunity to leave the waiting area, but still be contacted. Hospitals commonly use on-site paging for communication with staff and increasingly for contacting waiting patients when their appointment is due. On-site paging systems in hospitals, unlike wide area paging systems, are local area services. Pagers using the commercial FM band receive a subcarrier, called the Subsidiary Communications Authority, of a broadcast station. Other paging protocols used in the VHF, 400 MHz UHF, and 900 MHz bands include POCSAG and ERMES. Other radio bands used for pagers include the 400 MHz band, the VHF band, and the FM commercial broadcast band (88-108 MHz). This was useful for times when the pager was off or out of the coverage area, as it would know what pages were sent to the subscriber even if the subscriber never actually received the page. In the mid-1990s, some paging companies began offering a service, which allowed a customer to call their pager-number, and have numeric messages read back to them. Because of this, if a one-way pager is turned off or is not receiving a usable signal at the time a message is transmitted, the message will not be received and the sender of the message will not be notified of this fact. Since one-way pagers do not contain transmitters, one-way paging networks have no way to track whether a message has been successfully delivered to a pager. Unlike mobile phones, most one-way pagers do not display any information about whether a signal is being received or about the strength of the received signal. The ReFLEX protocol was developed in the mid-1990s. 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. When the person received an audible signal (a buzz) on the pager, the user found a telephone and called the service centre, which informed the user of the caller's message. ![]() The Bellboy was a terminal that notified the user when someone was trying to call them. #Motorola 700 mhz pager codes tvSolid-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. 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. ![]() Bellboy was the first commercial system for personal paging. telephone monopoly colloquially known as 'Ma Bell'-presented its Bellboy radio paging system at the Seattle World's Fair. ![]()
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