If I remember correctly, pagers started out being used by doctors, both in and out of hospitals (didn't some of the doctors in the House, M.D. tv show still have pagers)? A friend of mine who worked for the Red Cross had one so he could be notified in case of emergencies.
Then pagers got really popular with drug dealers and got a bad reputation. Motorola quickly rectified this by campaigning for parents to give them to teenagers to keep track of them and notify them to call home, trying to rebrand pagers as wholesome tools for families. They were also a status thing as they started being used by upscale/well-to-do families first.
Finally restaurants started using them with customers. If you had to wait for a table they'd give you a pager so you could leave the restaurant and didn't have to sit there while you waited, they'd just send you a message on the pager when your table was ready.