You might like Evan Doorbell's YT channel then – he has a lot of old tapes from his misspent youth traveling the world on Ma Bell's dime, and has posted a lot of videos explaining it all for a generation (like mine) without any frame of reference.

https://www.youtube.com/@evandoorbell4278

Evan's stuff is excellent and worth watching/listening to.

Shameless plug: if you like his stuff, you might also like my book, "Exploding The Phone", which is a history of phone phreaking. https://explodingthephone.com/

Evan narrated the Audible version. :-)

I enjoyed your book, made sense of a lot of things 13 year old me had stumbled upon that I could never get to work (as I was maybe 5 years too late).

That's awesome, thank you!

I very much recommend this book as well. Great read. Thanks for writing it!

Exploding The Phone was an excellent read.