Captain Crunch

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.

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