A real person at first, then later if I remember right, automated.
It was called "phreaking" when you fooled the phone with a simulation of the sound of coins. The beginning of the "hacker" culture...
walrus
On an only slightly related topic, area codes were assigned according to expected usage, not geographically. Because on dial phones, higher numbers kept circuits open longer, they used more electricity, denser populations got lower numbers. Sounds trivial, but with millions of calls it added up. Hence, NYC got 212 (numbers staring of ending with 1 were reserved for phone company use), LA 213 and Chicago 312.
I wish I knew when being "hacker" became a bad thing. I still have my copy of Steven Levy's book "Hackers" - it's about Bill Gates, Steve Jobs, etc. Early '80's classic. Being called a hacker used to be a compliment.
https://www.amazon.com/Hackers-Computer-Revolution-Steven-Levy/dp/1449388396
walrus
Back in the day, at least in the computer manufacturing business, a "hack" was an elegant, temporary work-around to a problem. The term "kludge" was probably just an industry-insider thing, but that was the awful, ugly, temporary work-around. As far as I know, there never was a "kludger" term for what ultimately became the meaning of "hacker" (as in negative connotations). A "hack" was not a negative thing. Creative hacking was something highly prized back in the day of discrete circuitry. Kludges were frowned upon unless they were *extremely* temporary.And by derivation the term "Hack" now used to depict jury-rigging or improvising something to be effective as a quick solution to a problem.
You guys are way smarter than me. I'm just a banker.
Interesting, though electrically 201 is higher use than 212 because of the 0 being a longer open circuit.And NJ got 201 because we invented the thing. Bell Labs was in Murray Hill NJ right down the street from where my dad worked. I was pissed when they split up the NJ area code and we went from 201 to 973 (and then 908).