davidb@pacer.com (David Barts) (02/21/90)
Can anyone recommend some good references on the internals of the phone system. By internals I am referring to things like ringback numbers, test circuits, types of exchanges and their capabilities (and vulnerabilities), etc. Info in various types of hardware would also be interesting. Also another thing that I have been wondering about is the three irritating tones you hear before the "We are sorry, the number you have dialed. . ." recording. I would guess they have something to do with automatic refunding of toll charges, because the times I've botched a number on a pay phone and got the recording, the phone spits back the money I put in it right after the three tones. In this case, what would there be to stop me from playing the tones every time I get or make a phone call? I'd assume there would be some mechanism to thwart this kind of theft. David Barts Pacer Corporation davidb@pacer.uucp ...!uunet!pilchuck!pacer!davidb