pager
A pager is a mobile receiver that preferably operates with frequency shift keying and is used in paging services such as Cityruf, Euromessage, Inmarsat paging or Ermes. Thanks to its high integration density, a pager has a size comparable to that of a cigarette pack. In the course of progressive miniaturization, it is now also available in wristwatch format or as a ballpoint pen. A pager is usually equipped with a display and an acoustic signal generator that produces a beep when a message is received.
There are pagers for different services and call classes, those that can be reached at a single address and others that can be reached at multiple addresses. Pagers are available with memory function and reminder function for unread messages.
The pager can only receive messages, it is not possible to send out information. Most paging systems, and therefore pagers, use the POCSAG code for signaling.
A new field of application for the pager, which can be seen as the forerunner of the short message service( SMS), is in private information services of business, sports or weather news. For these applications, there are special paging services that display the messages sent in the UHF range as text or in graphical form. For example, there are radio weather stations that inform the private user about the weather of the coming days with numerical data and icons.