[Corelatus] said recently that “someone” asked them to identify the phone signals in the 1982 film The Wall, based on the Pink Floyd song of the same name. We suspect that, like us, that someone might have been more just the hacker part of the brain asserting itself. Regardless, the detective work is fascinating, and you can learn a lot of gory details about phone network in-band signaling from the post.
The analysis is a bit more difficult because of the year the film was made. At that time, different countries used slightly different tone signaling standards. So after generating a spectrogram, the job was to match the tones with known standards to see which one best fit the data.
