On Saturday, Carl attended a local meeting of Ham Radio operators experimenting with the Amateur Radio Data Emergency Network (ARDEN). He has an ARDEN node that one of his fellow Hams has loaned him so Carl can become familiar with the ARDEN mesh network. The ARDEN mesh network can be used to pass text messages and phone messages using Ham radio frequencies when normal communication vehicles are in-accessible -- e.g. if cell towers are down, or internet is down. This can allow non-Ham individuals to get family health and welfare messages communicated in times of crisis.
Something that Carl want to make sure that I knew was that, in case of a personal or wider emergency, non-Ham operators are allowed to use Ham frequencies to make emergency communications.
Just might be of interest if you find yourself in an emergency situation, but your telephone or cellular service is in-operable, if you know where a Ham radio is located, you may be able to communicate out to request help by that method.