I was gonna reply in the phone show thread, but I think this topic needs it's own thread.
Emergency operator interrupting is done by calling up your local operator and asking them to interrupt a busy line. I used to do this back in the days before VoIP and cell phones. This makes it a dying art since land lines are slowly going away.
In 1990 - 1991, Chris Tomkinson and I had this sysop we hated and we would emergency interrupt his BBS line all the time, just to annoy his users. I think it must have been a free service back then because I know I wouldn't keep doing that if it cost money. I also used to interrupt BBS lines so that their lines would free up and I could log in. I remember some girl I used to talk to back then would occasionally interrupt my line when it was busy too. Weird that it's so crazy-expensive today.
Come to think of it, I remember operator interrupting from pay phones TO pay phones using my red box. I had a friend who hung out at a particular pay phones a lot and I would break in to say hi. And then I would interrupt random pay phones just to see if the people talking on them would release the lines. The charge from a pay phone was just a couple bucks. A lot less of a hassle than the $20 or so it costs today.
I'm going to play around with this some more, just to see what's possible today and how much it costs. Can you interrupt a wireless phone? I doubt it, but it's worth a try. I think interrupting a VoIP line would be impossible. I wonder if it's possible on digital cable phone lines.