jefmcg
Guru
I'd thought that the reason you got a dead line is that they want to make sure that their call centre droids are never idle, so a computer dials your number in expectation that an operator would be free. Sometimes they are not. The call centre would rather waste your time than have a worker sit for a few seconds waiting for you to pick up.
(but @classic33 might be right, I'm speaking hearsay)
(but @classic33 might be right, I'm speaking hearsay)