John Thomas Draper, also known as Captain Crunch, Crunch or Crunchman (after the Cap’n Crunch breakfast cereal mascot), is an American computer programmer and former legendary phone phreak. He is a widely known figure within the computer programming world and the hacker and security community and generally lives a nomadic lifestyle
Draper learned that a toy whistle packaged in boxes of Cap’n Crunch cereal emitted a tone at precisely 2600 hertz—the same frequency that AT&T long lines used to indicate that a trunk line was available for routing a new call. The tone disconnected one end of the trunk while the still-connected side entered an operator mode. The vulnerability they had exploited was limited to call-routing switches that relied on in-band signaling. After 1980 and the introduction of Signaling System No. 7 most U.S. phone lines relied almost exclusively on out-of-band signaling. This change rendered the toy whistles and blue boxes useless for phreaking purposes. The whistles are considered collectible souvenirs of a bygone era, and the magazine 2600: The Hacker Quarterly is named after the audio frequency.