This interview on Fresh Air goes into why pagers have continued to be used in hospitals (tl;dr: cell-phone communication gives a faster turnaround, but the lower barrier to communication means that people will go to the on-call person more often than they would with the beeper where they’re more likely to find their own solution).
Well, that article also mentioned the 'other service', i.e. FM, which more readily penetrates buildings and underground facilities and covers wider areas. And if there is a disaster, there's always the danger that remaining cells in the affected area are overcrowded.
https://www.npr.org/2023/12/15/1219737658/why-do-doctors-sti...