Originally published at: https://boingboing.net/2021/02/23/the-8bit-guy-on-the-art-of-phone-phreaking.html
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Love David Murray’s videos. Whenever he uploads a new one, that’s my viewing while I prep dinner.
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In 1987, in college, I simply went to a pay phone and called my dorm phone, where a friend held a mini cassette recorder to the earpiece. I then put quarters in the payphone. The sound this made, a quick beep beep beep beep beep, was recorded (a nickel a beep).
I had no idea if playing this tone back through the payphone to simulate quarters would work, I had never heard of anyone doing this before. I was really surprised when it did. My first long distance call test was to the Hard Rock Cafe in Helsinki. The crazy thing is, since this was a recording of not just the right tones, but the actual sound of the quarter falling through the phone, when I tried this with an operator on the line, it still worked. This only worked on certain phones though - other phones blocked the mouthpiece from working before a call was made, preventing playing the tones this way.
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For those interested in how telephone networks used to work, here is something to keep you busy for a month. Evan Doorbell's Telephone Tapes - Group 1 Playlist
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Much better content than his average videos*, I actually enjoyed this one!
Fun fact about DTMF:
‘Some’ years ago we had this young woman in our team: it did not matter how discriminating and sophisticated we made our DSP based DTMF receivers (yes the ones that went in the exchanges): she could always slip in a digit or two while talking with her normal voice!
(*) I don’t know if he oversimplifies stuff or he’s just confused in many of the videos I have sampled.
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“Ghost in the Wires” by Kevin Mitnick has some fantastic stories about his phone phreaking escapades. He even did it in prison!
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I had to unsubscribe to his channel. Why?
- Borrowing a prototype machine that didn’t belong to him and dremelling out screws, seriously damaging it before returning it
- Being an absolute shit to viewers who donate him stuff for his channel — “thanks, I guess. Don’t know what I’ll do with this.”
- Conducting “second amendment audits.” At Subway restaurants.
- Being an ass to the contractors who built his extension, devaluing their work and saying to his viewers that he could have done a better job, and then showing the lousy work he did. (I’m an electrician, so this one was extra grating)
Look, I know that he covers neat topics from time to time. There are just so many other better channels to choose from where people are discovering and rediscovering classic tech, and where I don’t have to support an absolute knob.
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Oh!
I totally missed the gun fondling part!
[brief youtube exploration, 
]
That and the assholish attitude nicely complete the picture of his 4-bit competence for me.
Thanks, I’ll find better ways to waste my time.
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I’ve run into this sometimes on VoIP, where I’ll randomly hear a digit when someone else speaks, as it’s usual to carry digits out-of-band on a VoIP call. One phone will mistake the voice for a tone, and then encode it as a digit and send it to the other end.
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Thumbs up for mentioning the Evan Doorbell tapes. They’ve been one of my favorites for years. I didn’t quite make it to phreakdom back in the day in spite of having the right mindset for it, and they cleared up a lot of details. I definitely missed out on some neat stuff, but then again I also missed out on getting fined or jailed for toll fraud, so it all balances out.
Exploding the Phone is another nice reference - and it revealed to me that one of my seemingly paranoid suppositions back in the day wasn’t far off-base, namely that there was always the potential for automated equipment to be listening for 2600 Hz. It detailed Project Greenstar, a 1960s-era automated mass surveillance system that was randomly deployed on toll trunks to catch phreaks. It listened for 2600 Hz at times when it shouldn’t be there, and would activate a recorder if it was detected, for the purposes of collecting evidence.
as it’s usual to carry digits out-of-band on a VoIP call
Yes, every time a voice codec is used (VoIP, mobile networks, etc.) DTMF needs to be carried out of band (and possibly reinserted at the remote end).
The same goes for all similar “in-band data” stuff: modems, fax…
The codecs, even the “wide band” ones, are tuned for human speech and would make a mess of the digits or modulation
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