A "Critical Message" is one for which it is vital that the information is delivered accurately, to the right people (or machines), and within a prescribed timescale (which is usually quite short – normally less than a minute but often much shorter).

Such a message might be sent for any number of reasons:

  • Emergency or disaster,
  • Terrorist Attack,
  • Chemical or Nuclear Accident,
  • Bad weather warning,
  • Business Continuity in the event of any of the above.

Whatever technology is chosen to deliver Critical Messages, it is imperative that it delivers the information to a "critical message" standard as listed above. It should not suffer either from the physical effects of an emergency (flood, bomb), nor deteriorate from congestion due to the very high number of calls that an emergency will generate.

Most mobile communications technologies suffer from one or both of these effects but radiopaging is almost immune to them.

CMA-E advises that for really critical situations, messages should be sent using more than one technology but that one of them should be radiopaging.