This is the way the telephone system worked while eliminating human switchboard ...

jagged-chisel on Jan 17, 2020 | parent | context | favorite | on: Quindar Tones: the beeps heard in recordings of as...

This is the way the telephone system worked while eliminating human switchboard operators. In-band signaling is what allowed the phreaks of the 60s and 70s to do what they did.