Before there were computer hackers, hackers of the 1960s and ‘70s, called phone phreaks, were intrigued by the structure of the new nationwide telephone network put together by AT&T.
The network’s machines communicated with each other by emitting tones of particular frequencies and in particular sequences, mainly 2600 hertz tones. Once the phreaks figured out the patterns of these tones, they could insinuate themselves into the system.
Around 1971 a Vietnam vet named John Draper discovered that the “Boson” whistle in Cap’n Crunch cereal boxes perfectly reproduced a 2600 Hertz tone. Simply blow the whistle into a telephone receiver to make free calls.
According to Apple Inc. co-founder Steve Wozniak’s words, with the ‘Cap’n Crunch “BO’SUN Whistle”, a phreaker could “seize a phone line.” Though many phreakers used instruments for the same purpose, the mass-produced whistle became iconic. Draper became known for using it, and gave himself the nickname “Captain Crunch.”