A semi-well known early phreaker known as Evan Doorbell, who is so well known in the normal world he doesn't even have a Wikipedia article, made a series of recordings (podcasts as the kids say) about how he became a phreaker.
These recordings don't just contain his personal history, but are full of great records of old busy signals, rings, phone company error recordings, and tons of insight into how a lot of the old stuff worked. They're extremely well edited as well, making them even more entertaining.
If you're interested in this kind of thing, I suggest you these out (mp3s taken from Phone Trips to save their bandwidth):
Episode 1 [ mp3 (00:25:24) @ 128kbps ]
Evan recounts how he first began getting curious with phones due to, what he felt, was an error message given in a slightly sexy manner. He reviews different error messages and error codes, and goes into how he speculated what different error codes meant. I think the most interesting aspect is how he talks about dialing special codes such as 660 (a "party line" out of Long Island, New York), figuring out how tones were different between the phones and phone company equipment, and some other insights.
Episode 2 [ mp3 (00:27:00) @ 128kbps ]
This begins in the summer of 1970 and how he's at summer camp and begins to broader his experimentation with the phone network. Including: how dialing 1 before an area code did not work where he lived, yet the phone company said to do this way; how the phone company changed their dial tone in 1965 (in his city); test circuits; and getting into figuring out how all of these things had to do with the type of switching equipment. And also, exploring phone prefixes, phone intercepts, and more.
Episode 3 [ mp3 (00:20:00) @ 128kbps ]
In this one Evan goes down to Atlanta, Georgia on a family trip and discovers more differences between Atlanta and Long Island.
Episode 4 [ mp3 (00:30:25) @ 128kbps ]
Interesting codes (prefixes, half numbers, etc) out of Long Island, NY in the late summer of 1970.
Episode 5 [ mp3 (00:32:42) @ 128kbps ]
Evan gets his own phone line as a teenager on a new prefix and tons of new things open up.
Episode 6 [ mp3 (00:34:50) @ 128kbps ]
An overview of the old billing "message" units, as used in the New York area in the 1970s. Even more recordings and information into party lines, phone switches, etc.