> A phreaker going by Joybubbles was the first to exploit the tone by whistling.
Joybubbles (formerly Joe Engressia) specifically denied being the first. In this interview (no timestamp), he mentions having heard of others phreaking as far back as the 50s: https://www.2600.com/offthehook/mp3files/1991/off_the_hook__...
He also demonstrates whistling 2600hz during that interview, including doing so on one of the only US trunks in service at the time still using it for supervision.
> Later, a toy whistle in a cereal box was found to be able to produce the tone, leading to further exploit by John Draper, aka, Cap'n Crunch.
Not true, even he admitted, belatedly, that Denny Teresi introduced him to it:
> https://www.dailydot.com/debug/john-draper-beyond-the-little...
> Denny called me and told me about this whistle that blew the magic tone that disconnects long distance phone calls, and that he had a spare. He asked me if I could drive him to San Francisco so he could show me how it worked.