Pagers were communication devices, usually used to contact people in emergencies, such as doctors.
In 1993, Professor James Rafferty placed light beams in his study which, if broken, would set off his pager. (PROSE: The Dimension Riders)
On 19 May 1998, the failure of the Galaxy IV communications satellite crippled the US pager networks, forcing doctors to remain in hospitals at all times in order to be in contact. (PROSE: Millennium Shock)
In 1998, General Howard Kane's pager went off when he was summoned by the Pentagon. (PROSE: Option Lock)
In 1999, Grace Holloway's pager went off when she was summoned by Walker General Hospital. (TV: Doctor Who)
Pagers were still in use in the 40th century. Chase Carrington usually summoned Sox by pager. (PROSE: Placebo Effect)
On a human colony planet, the Eighth Doctor stole a pager from a hospital doctor so that Fitz Kreiner could keep in contact with him. (PROSE: Vanishing Point)