The sound of the dialup, pictured (2012)

Re:The sound of the dialup, pictured (2012) by antiterra on Tuesday March 30, 2021 @09:46PM (#26642664)

I really like how you can figure out the phone number dialed with the representation of the DTMF tones. This was basically an audio coordinate system (or just a 2D array): an X tone and a Y tone played at the same time.

The upper component has three positions representing the columns on a phone keypad.

The lower four positions represent the rows.

For example, zeros are represented by upper tone 2 for the middle column (2,5,8,0) and lower tone 4 for the bottom row (*,0,#).

[ Parent | on HN ]

Re:The sound of the dialup, pictured (2012) by Jtsummers on Tuesday March 30, 2021 @09:54PM (#26642718)

https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_sign...

There was a fourth column (A,B,C,D) meant for menu selection, and for the US military to indicate call precedence. Also used for various kinds of system automation and signaling but not accessible directly.

[ Parent | on HN ]

Re:The sound of the dialup, pictured (2012) by lozf on Wednesday March 31, 2021 @05:34AM (#26645190)

Generate them all with:

      sox -n dtmf-1.wav synth 0.1 sine 697 sine 1209 channels 1
      sox -n dtmf-2.wav synth 0.1 sine 697 sine 1336 channels 1
      sox -n dtmf-3.wav synth 0.1 sine 697 sine 1477 channels 1
      sox -n dtmf-4.wav synth 0.1 sine 770 sine 1209 channels 1
      sox -n dtmf-5.wav synth 0.1 sine 770 sine 1336 channels 1
      sox -n dtmf-6.wav synth 0.1 sine 770 sine 1477 channels 1
      sox -n dtmf-7.wav synth 0.1 sine 852 sine 1209 channels 1
      sox -n dtmf-8.wav synth 0.1 sine 852 sine 1336 channels 1
      sox -n dtmf-9.wav synth 0.1 sine 852 sine 1477 channels 1
      sox -n dtmf-0.wav synth 0.1 sine 941 sine 1209 channels 1
      sox -n dtmf-star.wav synth 0.1 sine 941 sine 1336 channels 1
      sox -n dtmf-pound.wav synth 0.1 sine 941 sine 1477 channels 1
      sox -n dtmf-A.wav synth 0.1 sine 697 sine 1633 channels 1
      sox -n dtmf-B.wav synth 0.1 sine 770 sine 1633 channels 1
      sox -n dtmf-C.wav synth 0.1 sine 852 sine 1633 channels 1
      sox -n dtmf-D.wav synth 0.1 sine 941 sine 1633 channels 1

      sox -n dtmf-us-busy.wav synth 10 sine 480 sine 620 channels 1
      sox -n dtmf-rbt-US.wav synth 10 sine 440 sine 480 channels 1
      sox -n dtmf-uk-us-dialtone.wav synth 11 sine 350 sine 440 channels 1
      sox -n dtmf-uk-busy.wav synth 10 sine 400 channels 1 # needs cadence
      sox -n dtmf-uk-ringback synth 10 sine 400 sine 450 channels 1
      sox -n dtmf-eur-dialtone.wav synth 10 sine 425 channels 1
      sox -n dtmf-eur-busy.wav synth 10 sine 425 channels 1 # needs cadence
      sox -n dtmf-eur-ringback.wav synth 10 sine 425 channels 1 # needs cadence

[ Parent | on HN ]

Re:The sound of the dialup, pictured (2012) by antiterra on Wednesday March 31, 2021 @10:23PM (#26655953)

I had forgotten about those! I had a phreaking program[1] with those on the C-64. They called the DTMF utility 'Silver Box.'

Turns out: https://en.wikipedia.org/wiki/Silver_box

[1] It was this one: https://commodore.software/images/jdownloads/screenshots/tel...

[ Parent | on HN ]

Re:The sound of the dialup, pictured (2012) by flemhans on Wednesday March 31, 2021 @02:35AM (#26644148)

And they sounded _weird_. Almost spacey.

[ Parent | on HN ]

Re:The sound of the dialup, pictured (2012) by pwg on Tuesday March 30, 2021 @09:51PM (#26642694)

You have also just described how the old analog touch tone phones actually generated the tones. Each column of buttons generated a different tone per column, and each row also generated another tone per row. A given button when pressed activated a column and a row to generate the two tones associated with that button.

[ Parent | on HN ]

Re:The sound of the dialup, pictured (2012) by antiterra on Wednesday March 31, 2021 @10:20PM (#26655930)

Yes, that's what my intent was.

[ Parent | on HN ]

Re:The sound of the dialup, pictured (2012) by grishka on Thursday April 01, 2021 @07:47AM (#26659242)

Where I'm from we used pulse dialing. I remember being so proud of myself for figuring out that the number of pulses the phone sent represented the digit you're dialing.

[ Parent | on HN ]

Re:The sound of the dialup, pictured (2012) by yaml-ops-guy on Tuesday March 30, 2021 @09:51PM (#26642687)

This was basically an audio coordinate system (or just a 2D array): an X tone and a Y tone played at the same time.

Auditory....Vectors? (Thinking aloud)

[ Parent | on HN ]

Re:The sound of the dialup, pictured (2012) by femto on Tuesday March 30, 2021 @10:52PM (#26643022)

The Quadrature Amplitude Modulation used by the modem (the last part of the sequence, which sounds like white noise) really is a sequence of auditory vectors.

[ Parent | on HN ]

Re:The sound of the dialup, pictured (2012) by gugagore on Tuesday March 30, 2021 @11:33PM (#26643228)

Humans can't hear a phase difference.

[ Parent | on HN ]