Phreakers were/are telephone system hackers. Back in the day it was possible to hack telephone systems using simple electronics and some technical knowledge. Th

Phreakers were/are telephone system hackers. Back in the day it was possible to hack telephone systems using simple electronics and some technical knowledge. The page being linked to seems to go into some of the history of phone phreaking. Incidentally, the following clip contains the most impressive demonstration of phreaking I've ever seen, showing a blind phreaker with perfect pitch called Joe Engressia who was able to hack the phone system just by whistling: https://www.youtube.com/watch?v=vVZm7I1CTBs https://www.youtube.com/watch?v=vVZm7I1CTBs A fair amount of the hacker culture of the 80s and early 90s (hacker in terms of what the common perception of a hacker is) seems to owe its debt to the trail blazed by phreakers.