In old movies when the cops told someone to 'Keep him on the line while we trace the call".

Cliff noticed that the hacker was creating user accounts for later use with the names “hunter,” “jaeger,” “benson,” and “hedges.” He concluded from this that the hacker spoke German (“Jaeger” is the German word for “hunter”) and smoked Benson and Hedges.

I read The Cuckoo’s Egg about five times, and lend it out often. I’ve got two copies. It’s probably my favorite book after Surely You’re Joking, Mr. Feynman.

I recall one scam (in North America) was the “Bank Inspector” or some such (We think one of our tellers is a crook. We need to test, could you take out $X and our inspector will pick it up and re-deposit it.").

One method the con artist would use was to say “if you are skeptical, call me back at the bank’s number…” They would then not hang up, but play a dial tone and have someone stand by to pretend to be the operator at the bank. This apparently worked because with mechanical switches, as long as the caller did not hang up the line stayed connected.

yes, I recall some movies or TV shows which showed the phone company workers running through banks of switches, calling out connection numbers to trace it back to the originating wire. Of course, they might then trace it to a trunk line to a different exchange, where the same process repeated…

Somewhere in the 60’s or 70’s they implemented a process (I recall reading about it) where if they put a certain signal on the line the line would stay connected even if the caller hung up.

Of course, once they started going electronic it was trivial to trace. The cliché in the movies then was “we traced it back to a mechanical exchange where we lost it.”

There was a movie, can’t remember the title, which did an inversion of this trope. The bad guy stayed on the line long enough for the cops to complete the trace, and they rushed to the location – only to find two pay phone handsets taped together.

I think that was used by the protagonist in F/X.

Donald E Westlake’s Why Me? in 1983 does this, but more subtly – jumpered wires from one pay phone to another, … to a phone in an empty, abandoned apartment.

I saw the same thing. I’ve got an inkling it was an episode of Starsky & Hutch, but I’m not sure.

So how do they actually trace calls now?

And of course, “Taken” (The original movie) did this in Paris with cell phones taped together.