A hacker in the 70’s John Draper found that a toy whistle in the cereal Cap’n Crunch blew at the same frequency that was used by AT&T long lines to indicate that a trunk line was ready the route a new call, essentially allowing him to make free long distance calls.
John Draper (born 1943), also known as Captain Crunch, Crunch or Crunchman (after Cap’n Crunch breakfast cereal mascot), is an American computer programmer and former phone phreak. He is a legendary figure within the computer programming world and the hacker and security community. Draper has long maintained a nomadic lifestyle; as of May 2013, he resides in Las Vegas, Nevada.
While Draper was driving around in his Volkswagen Microbus to test a pirate radio transmitter he had built, he broadcast a telephone number to listeners as feedback to gauge his station’s reception. A callback from a “Denny” (identified in a Discovery Channel documentary as Denny Teresi) resulted in a meeting that caused him to blunder into the world of the phone phreaks. Teresi and a large percentage of the phone phreaks were blind. Learning of his electronic capability, they wanted him to build a multifrequency tone generator (the “blue box”) to gain easier entry into the AT&T system, which was controlled by tones. Then they would not have to use an organ and cassette recordings of tones to get free calls. A blind boy who had taken the moniker of Joybubbles had perfect pitch and was able to identify the exact frequencies. They informed him that a toy whistle that was, at the time, packaged in boxes of Cap’n Crunch cereal could emit a tone at precisely 2600 hertz—the same frequency that was used by AT&T long lines to indicate that a trunk line was ready and available to route a new call. This would effectively disconnect one end of the trunk, allowing the still connected side to enter an operator mode. Experimenting with this whistle inspired Draper to build blue boxes: electronic devices capable of reproducing other tones used by the phone company.
I don’t do that. I don’t do that anymore at all. And if I do it, I do it for one reason and one reason only. I’m learning about a system. The phone company is a System. A computer is a System, do you understand? If I do what I do, it is only to explore a system. Computers, systems, that’s my bag. The phone company is nothing but a computer.