Was going to make the same suggestion. The Evan Doorbell tapes you link to are great for learning about that lost world. I can remember that when I was a kid,

Was going to make the same suggestion. The Evan Doorbell tapes you link to are great for learning about that lost world. I can remember that when I was a kid, once you started dialing, the phone would go silent--almost. What you would actually hear was hiss, ghostly clicks now and then, and, occasionally, very quietly, down near the noise floor, short bursts of tones - beep boop boop beep boop beep! I learned about blueboxes and the like later (in what were histories by then) and I know what I was hearing was some kind of crosstalk, but I never found out whether the tones were MF tones (one telco switch signaling to another to set up the call, in the voice band, but just before the phones on either end were patched into the circuit) or (similar, but different) DTMF tones from modems and fax machines on the local circuit. (I vaguely remember occasionally hearing tentative tones like from a real person pressing buttons.) All the electromechanical hacks from the midcentury systems that were sometimes still in place in the 80s and even 90s are fascinating -- the earliest direct dial systems had to set up the connection digit by digit because they had no memory. Later they invented systems that could remember some of the digits by temporarily connecting your circuit to a literal mechanical stepper on the telco end that would replay those digits to the next switch down the line (and then disconnect) once you had dialed enough digits to fill it up.