when a national disaster strikes or an EMP or w/e.. all federal and local radio's will be out
HAM and short wave operators will be the only ones with communications... so.... they license the operators and give them call numbers.. plus in FL special license plates to identify them in times of crisis..
thats what I remember being told
here is the wikipedia entry
http://en.wikipedia.org/wiki/HAM_radio
I'm kinda interested in it now.. More research to follow