The lesson about in-band vs. out-of-band signaling is a good one, even if the specifics of blue boxing aren't discussed. The evolution of panel-pulsing to MF to

The lesson about in-band vs. out-of-band signaling is a good one, even if the specifics of blue boxing aren't discussed. The evolution of panel-pulsing to MF to SS7 is interesting, and knowing some of that history provides context to why some things are the way they are today in voice telephony.