2600: The Hacker Quarterly is an American seasonal publication of technical information and articles, many of which are written and submitted by the readership, on a variety of subjects including hacking, telephone switching systems, Internet protocols and services, as well as general news concerning the computer "underground." With origins in the phone phreaking community and late 20th-century counterculture, 2600 and its associated conference transitioned to coverage of modern hacker culture, and the magazine has become a platform for speaking out against increased digital surveillance and advocacy...

2600 hertz (2600 Hz) is a frequency in hertz (cycles per second) that was used by AT&T as a steady signal to mark currently unused long-distance telephone lines. During the 1960s, in-band signaling was used, so the same line for both voice conversations and telephone connection management signals. Since a pause in a voice conversation would produce silence, another method was required for switches to determine whether a line was in use. The solution AT&T created was to produce a 2600 Hz tone on idle trunks. == In phreaking == In phreaking, a device known as a blue box was used to generate the 2600...