Pagers are communications devices that use radios to receive messages sent from a paging controller. Pagers operate on a system that may include one or many pagers in total.
Pagers listen to one radio frequency all the time and have a specific address, called a Channel Access Protocol code, that lets it know which message is addressed to an individual pager. When the pager receives a message that has its unique code, it alerts the user and may provide more information, depending on what type of pager is in use. As of 2014, hospitals and restaurants use pagers to instantly communicate important information to those who need it.