I've read in various corners of the internet (including on HackerNews, here: https://news.ycombinator.com/item?id=3224897) that, at some point in history, people used to be able to "scream" a sound into a telephone handset such as to cause a 300 baud modem to respond.
However, I can find no actual recording of this.
Does one exist?
If not, can one among you make one?
http://www.windytan.com/2012/11/the-sound-of-dialup-pictured...