When I worked in the hospital we had hospital pagers that worked for about a 5-10 mile radius and operated on an abbreviated paging system (never did figure out how to page from an outside line).

For the person oncall we rotated a pager with a statewide range.

With my new job, the tech support people wear a pager. They receive pages from our call center. I assume it has pretty fair range since most of our tech support live about 40 miles away.

Pagers are good because there is the expectation that you will be calling the person back so you have a few minutes to collect yourself and prepare. With a cell phone call you either answer then or let it go to voice mail with no real expectation of an immediate call back.

Nothing sucks more than waiting forever for a returned page though.