The old system would disable the dial if no coin was deposited, however, the hook switch (rest) would still pulse the line. When the handset was lifted a resistance was put across the line allowing current to flow. At this point the line would supply dial tone and listen for dial pulses. The strowger or crossbar exchanges of the day were set up to also allow zero and nine to be dialled without detecting a coin drop, the UK emergency number is 999 and operator was simply dial zero. An engineer with a keen ear in the exchanges would notice slight irregularities between rotary dialed numbers and tapped numbers. The mechanical exchange wasn't that smart. I have had to resort to tone dialers in Indonesia to use a phone card because they disable the # key . Their phone systems were largely owned by kleptocrats who realised that phone cards would bypass their exorbitant phone call charges.
On Sun, Mar 1, 2020, 06:22 Paul Gilmartin < 0000000433f07816-dmarc-requ...@listserv.ua.edu> wrote: > On Sat, 29 Feb 2020 13:34:04 -0500, Bob Bridges wrote: > > >That's a new one on me. How did tapping instead of dialing save you the > fourpence? I'd have thought that whatever allowed the call to go through > a) didn't know the difference between tapping and dialing, and b) wouldn't > go without being paid. > > > Coin-slot phone? I understand American pay phone appeared open-ciruit > until a switch was closed by weight of a coin. (Ringer is higher voltage > AC.) > > Operator-assisted calls relied on operator's hearing coins drop. Cheaters > could spoof those sounds with hand-held bells. > > UK might be different. I don't see how tapping bypassed the protocol. > > One might save a couple seconds by tapping faster then the dial reset. > > >-----Original Message----- > >From: Wayne Bickerdike > >Sent: Saturday, February 29, 2020 01:42 > > > >Phone tapping was something we did in the 60's in my first job. We lived > in > >a YMCA hostel with a single payphone and to save 4d (the price of a local > >call) you dialled zeroes and nines and tapped the other numbers. My > >girlfriend's number in the local village was easy, Harwell 300. On > >occasions a line engineer in the exchange would interrupt and tell at you > >for not paying. > > -- gil > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
