Some more information would be nice. How did it work, what could you do, what country was that in?
I could call any phone numbers for free, including international of course.
Somehow after one hour or so the call could be terminated, but I could call again.
None of the numbers I've called (mainly in the US: friends) have ever being charged for this.
It worked in Italy, when the national owned phone company (the only existing) was still called "SIP" (funny name, eh?): in 1994 was then renamed into current "Telecom Italia"; It was around 1986.
How did it technically work?
I don't recall if it was a rotary dial phone or not, but I had dial "1,1,1", then (and this was the tricky part) I had to give a fast smash down to the metal holder of the receiver: then I could hear the typical sound of a line ready. I would say the "smash the holder" necessary step worked very well in one out of ten public phones, and only some times in one out of five.
I remember I told about this to many friends, but at that time I was one of the few that had somebody to call abroad :)
I recall now my friend started using it to call his father which was working in Venezuela (pretty rich, was one of the owner of a building company in Caracas): funny enough he soon stopped using it since he had to move to the street to call, while it was much easier for his father to call him for free from Caracas: how? he would just corrupt an operator working in the national Venezuela's phone company: the operator would provide his father a free phone line to call abroad.
Years later the father left Venezuela, as many other, and he personally told me the reason: "we had to leave that country: too much corruption" (!) ...pretty bad, eh?
* 113 would call the police
* 112 the "carabinieri" (another police)
* 115 fire dep.
* 118 hospital (it was)
* 117 financial police...
so I always suspected that '111' I (ab)used had sure something to do with an emergency line.
"the typical sound of a line ready" -> dial tone?
What would you normally hear when you picked up the receiver on a payphone, before you inserted coins? In my US experience in the 90s, if I were using a payphone, I'd pick up, listen for dial tone, insert my coins, (hear the coi tones, dial tone would pause and come back, IIRC), then dial the number, etc. If I just dialed a number without insering coins, I'd get a recorded announcement that I needed to insert coins; unless it was a free call. From movies, I gather older pay phones didn't let you make free calls generally, you'd need to insert coins before the dial tone; maybe that was common where you lived too?
As I understand it, the payphone phone lines I interacted were specially configured and had additional signalling so the phone company could determine free or paid at the central office and the payphone would signal payment. Private payphones existed where the phone line was normal and calling rates were determined by the phone itself, but it's trickier to do that right.
It makes some sense that a private payphone that would let you make free calls to the 11X numbers might have a synchronization issue. Dialing 111 wouldn't ever connect anywhere in Italy (I think?), but might have triggered the call is paid behavior, and hanging up quickly may have cancelled actually dialing without the phone realizing. There's a lot of tricky timing with detecting hang ups, and exploiting differences in timing gets you into being a phreaker.
As for who paid, if these were private payphones, probably the owner of the phones. Otherwise, the phone company.
You might enjoy this series of audio recordings: http://www.evan-doorbell.com/production/group1.htm
There were, of course, ways to play the coin insert tones.
YES
> "the typical sound of a line ready" -> dial tone?
YES
It was exactly what "docbert" explained above (happening in Australia)
> , you'd need to insert coins before the dial tone; maybe that was common where you lived too?
YES: without coins we had, if I recall correctly, a long non-stop constant tone, while with the coin it changed into the "you can call now" tone: "to, toooo"
> Dialing 111 wouldn't ever connect anywhere in Italy (I think?),
you a right
> There's a lot of tricky timing with detecting hang ups, and exploiting differences in timing gets you into being a phreaker.
ah, I got it
> As for who paid, if these were private payphones, probably the owner of the phones. Otherwise, the phone company.
yes, all calls from a public phone, but call abroad, so I guess the company "SIP" had to pay for it: not good, I know :(
thank you Toast0!