The average consumer is most likely to see pagers today in old episodes of the series “Emergency Room.” The small device was the predecessor to the cell phone. The basic idea: If you want to talk to someone, you ping their pager. The person sees a phone number (or a short message) and can call back or take action based on the message.
Pagers have been widely used, especially for emergency services, since the 1980s. However, the ubiquitous mobile phone has made them almost redundant due to their constant availability. Fire departments, for example, still use some of them. There are now even models of pagers that can send messages back.
There is a simple reason why militias like Hezbollah use pagers so widely. Unlike cell phones or smart phones, their whereabouts cannot be traced. A regular pager is just a receiver that is not logged into the network. It is not a problem to activate all the pagers in an area at the same time.