Joybubbles is a forthcoming, feature-length documentary about Joe "Joybubbles" Engressia Jr., a blind hacker considered by many to be the father of phreaking, the systematic manipulation of telecommunication systems.
Writes Rachael Morrison, who is currently seeking funding for the documentary on Kickstarter (with 52 hours to go as of this posting, the project is less than $1,500 from its goal):
Joe Engressia, Jr. was born blind in 1949 in Richmond, Virginia. At an early age, he developed an interest in the communicative power of the telephone. Gifted with perfect pitch, he realized that if he whistled the exact tone of 2600Hz into the telephone receiver, he could make free phone calls and explore the inner workings of the telephone network. His incredible skill for hacking the network eventually awarded him the nickname "The Whistler," and he became famous among a group of underground telephone hackers who called themselves phone phreaks. The phone phreaks were mainly active in the 1960s and 1970s, when the telephone network was based on a system of tones.
If you're looking for a primer on Engressia, or phreaking in general, I highly recommend the following episode of Radiolab, titled "Long Distance":
H/t Laughing Squid