Yes. Details under "Publication History": https://en.m.wikipedia.org/wiki/2600:_The_Hacker_Quarterly

And "Blue Boxes" exploited the 2600Hz signal to make free phone calls, explained here under "Operation": https://en.m.wikipedia.org/wiki/Blue_box

Steve Wozniak built Blue Boxes and Steve Jobs sold them: https://artsandculture.google.com/asset/blue-box-designed-an...