In-band Signaling
A signaling method in which control signals and user data are transmitted over the same channel, carrying the security risk of forgery.
Timeline (last 90 days)
The principle of the blue box is based on the in-band signaling system used by AT&T's long-distance network: in early telephone networks, control signals shared the same 4kHz channel as voice and were represented by tones of specific frequencies.
A continuous tone of 2600Hz would be recognized by the switch as an idle line, allowing hackers to take over trunk lines and send their own routing tones, achieving free long-distance calls.
All Facts (2)
The principle of the blue box is based on the in-band signaling system used by AT&T's long-distance network: in early telephone networks, control signals shared the same 4kHz channel as voice and were represented by tones of specific frequencies.
50%UnverifiedA continuous tone of 2600Hz would be recognized by the switch as an idle line, allowing hackers to take over trunk lines and send their own routing tones, achieving free long-distance calls.
50%