A good place to start is the "How Evan Became a Phone Phreak" recordings. Though it's about someone dealing with electromechanical switching equipment in the se

A good place to start is the "How Evan Became a Phone Phreak" recordings. Though it's about someone dealing with electromechanical switching equipment in the seventies, it's surprisingly parallel to how a lot of people get into phones today. Dialing Those Mysterious "1xx" and "0xx" Codes is another good one, as is the 052 conference.