The last time a regular consumer would have seen a pager might have been during an old episode of the popular US television series “ER.” These small devices were something like a precursor to mobile phones. The basic idea was that if you wanted to talk to someone, you would ping the person’s pager. They would see the phone number – or a short message – and could call back or act according to the message. Pagers were widely used from the 1980s onwards, especially by emergency services. But the ubiquity of mobile phones has largely made them redundant. Some fire brigades still use them, to some …