Hi Dr J,

I just found a write-up on the subject:

.There was never an Oscar Meyer Weiner whistle that I can recall, but there was a Captain Crunch whistle. What happened here is that in the late ‘60s or early ‘70s (I can’t recall exactly when), someone discovered that a cheap toy whistle given away as a little prize in boxes of Captain Crunch breakfast cereal in America would blow at a tone of just about exactly 2600 hz. Thus you could blow the whistle into the phone, trick the phone company into thinking you’d hung up, and start dialing and playing all kinds of other things without being billed.

This was totally on accident of course. The Captain Crunch people, and whoever actually made the whistles, did not intentionally create such a whistle. It just happened that that was the frequency the whistle created when blown.

On the old phone system, everything was controlled by simple tones. 2600 hz was the tone your phone sent to the system whenever you hung up. Thus, if you generated that tone without hanging up, you were effectively on the system without anyone knowing it. You could make free phone calls to anywhere, and if you had a way of generating other tones, you could do even more to play with the system.

The Captain Crunch whistle was very limited; other much more sophisticated tone generators were used by many phreakers. I even read at one time about a blind gentleman with perfect pitch who could blow 2600 and all kinds of other tones just by whistling—which may sound like a legend, but is actually QUITE believable. The old phone system did EVERYTHING with just a few simple tones, and none of them were difficult to duplicate.

The whistle was more of an item of amusement for the "phreaking" community than anything else I think.

By the way, all of this is more or less irrelevant now; most of the world is now on electronic, digital switching, and those old tones don’t do anything anymore.

I shouldn’t be considered a ‘primary source’ on any of this, though for a while there I did used to do a lot of phreaking, back when I was under 18. But that was in the ‘80s, and near the end of the big era of pirating phone usage. But I did read a whole lot of the underground literature of that day, and did do some playing myself . . .