I got to this from a BoingBoing post which sent me to this link:
1971 Esquire article -
""That's 2600 cycles per second to be exact," says Lucey. "Now, quick. listen."
He shoves the earpiece at me. The ringing has vanished. The line gives a slight hiccough, there is a sharp buzz, and then nothing but soft white noise.
"We're home free now," Lucey tells me, taking back the phone and applying the blue box to its mouthpiece once again. "We're up on a tandem, into a long-lines trunk. Once you're up on a tandem, you can send yourself anywhere you want to go." He decides to check out London first. He chooses a certain pay phone located in Waterloo Station. This particular pay phone is popular with the phone-phreaks network because there are usually people walking by at all hours who will pick it up and talk for a while.
He presses the lower left-hand corner button which is marked "KP" on the face of the box.
"That's Key Pulse. It tells the tandem we're ready to give it instructions. First I'll punch out KP 182 START, which will slide us into the overseas sender in White Plains." I hear a neat clunk-cheep. "I think we'll head over to England by satellite. Cable is actually faster and the connection is somewhat better, but I like going by satellite. So I just punch out KP Zero 44. The Zero is supposed to guarantee a satellite connection and 44 is the country code for England. Okay . . . we're there. In Liverpool actually. Now all I have to do is punch out the London area code which is 1, and dial up the pay phone. Here, listen, I've got a ring now."
I hear the soft quick purr-purr of a London ring. Then someone picks up the phone. "Hello," says the London voice.
"Hello. Who's this?" Fraser asks.
"Hello. There's actually nobody here. I just picked this up while I was passing by. This is a public phone. There's no one here to answer actually."
"Hello. Don't hang up. I'm calling from the United States.""
Calling a random payphone to talk with a stranger - kinda like random poking on facebook. Which I don't do much of. Perhaps I'll start.