2600
- The frequency in hertz that AT&T originally used to indicate when a line is free. In 1974 John Draper aka Captain Crunch discovered a breakfast cereal children's was capable of making this tone. He and others used this technique or similar techniques in conjunction with a blue box to generate the 2600 hertz tone and make free long distance calls around the world. These individuals came to be known as phreaks.
- 2600 is also a commonly used name for news or information containing information about hacking and phreaking.
- Name commonly associated with the early Atari VCS (Video Computer System) gaming system.
Also see: Phreak, Security definitions
