Evan Doorbell's Telephone Tapes

This is the personal site of Evan Doorbell, who was one of the big phone phreaks in the 70's along with people like Mark Bernay. He recorded all the old telephone sounds and put them into different series where he explains how the old telephone system worked.

His "How Bell Became a Phreaker" tapes are where I first encountered the genre of "Hacker stories that start at the beginning." and it's still one of my favorites even though it's incomplete.[0]

Some notable tapes in this collection:

How Evan Doorbell became a Phone Phreak, parts 1 through 6 (Incomplete)

Phreaks from Esquire article on "052" conference, parts 1 and 2 (January, 1972) [The Secrets of The Little Blue Box esquire article[1]]

MF Boogie numbers one and two (Music made from phone tones, actually composed on an electronic organ during a conference call with NPR reporters. [2])

[0]: https://news.ycombinator.com/item?id=8452591

[1]: http://explodingthephone.com/hoppdocs/rosenbaum1971.pdf

[2]: Lapsley, Phil. Exploding the Phone, The Untold Story of The Teenagers and Outlaws Who Hacked Ma Bell. New York: Grove Press, 2013. 230.

If you're building fault-tolerant systems, understanding how #5 Crossbar worked is still worthwhile. That was the peak of electromechanical telephony, and understanding how it dealt with faults is valuable. There are multiple resources available for almost everything - originating registers (which receive dial pulses), senders (which forward call info to other exchanges), markers (the brains of the system, with two self-checking halves), and specialized resources such as trouble recorders and billing punches. As a call progresses, resources are "seized" for a short period, then released. Resource seizure normally rotates through the resource or is random, for load balancing.

If something goes wrong, there's one retry, with different resources than the first time around. Then the call is abandoned. If the failure rate is 1% per attempt (remember, this is all done with electromechanical relays), the failure rate on two tries is 0.01%. Retry after two failures probably has a cause other than a transient error, and results in seizure of a trouble recorder, which dumps the state of the call into a specialized punched card.

In the entire history of the Bell System, no electromechanical exchange was ever down for more than 30 minutes for any reason other than a natural disaster. This record was not maintained in the computer era.

This guy has a beautiful speaking voice. I'm sure it didn't hurt when it came to social engineering his way around the phone network.

Here is an even more extensive set of recordings:

http://www.wideweb.com/phonetrips/

He's got a great voice, and explains it very well. The large repository of clips, finished or not, is very impressive.

I enjoyed the Z ZZ ZZZ dial a joke line one. Thanks for posting.

Wow. I'm completely floored at how deep this person got into the world of phones. I was also obsessed with phones for a while, and consider my ears my favored input channel, but I didn't take 10 steps to this guy's marathon. Memorizing tons of specific rings and dialtones, recognizing weird audio quirks of specific switches, etc. This is amazing. No matter what you study, there always seems to be as much detail as you have the time and energy to appreciate.