Audible sounds to change channels. It's a form of brilliant engineering I've always wondered about.
Between this and Captain Crunch whistles for long distance access tones, classic technology ALWAYS wowed me.
The long distance 2600 Hz trick stopped working in the 80s. The height of popularity was in the late 60s early 70s I believe.
Replying to @matthartley@fosstodon.org
@Fishd ohh yeah, sound cards would have been awesome for this!
@matthartley Phone phreaking was active through the 80s and 90s with sound cards producing the tones needed to break operator control ... no cereal required .... so I'm told. 😳
@Fishd True. Used to do something in the 80s with payphones.
If memory serves me, 971, last four numbers, hang it up multiple times (3?) then it started ringing. Presumably a ringer check. 😁
@matthartley My IT origin story involves a leaked copy of the original Wolfenstein 3D, a friend with an Amiga, two modems and a loop line in NYC.
He used to try to get me to laugh during the setup ... as I'd get a US operator saying things like "Hello, I have a collect call from Austin Maestro... will you accept?" which is a bit like saying you had a collect call from AMC Pacer ...