Technically, all the stuff heard at the beginning was initialization and training stuff. The actual data is the uniform hiss/roar just before the speaker cut o

Technically, all the stuff heard at the beginning was initialization and training stuff. The actual data is the uniform hiss/roar just before the speaker cut off. https://www.theatlantic.com/technology/archive/2012/06/the-mechanics-and-meaning-of-that-ol-dial-up-modem-sound/257816/ https://www.theatlantic.com/technology/archive/2012/06/the-m... At least for modems near the end of the period. The very first ones at 300bps really did sound like cassette audio.