Topic summary
In-band
Extracted from the Wikipedia article In-band signaling.
Telephony
In-band signaling is insecure because it exposes control signals, protocols and management systems to end users, which may result in falsing. In the 1960s and 1970s, so-called phone phreaks used blue boxes for deliberate falsing, in which the appropriate tones for routing were intentionally generated, enabling the caller to abuse functions intended for testing and administrative use and to make free long-distance calls.