TELECOM Digest OnLine - Sorted: Re: TV Show - Legacy Phone in Scene

Re: TV Show - Legacy Phone in Scene

Paul Coxwell (
Fri, 21 Oct 2005 00:09:39 +0100

> In the city, payphones for prepay, even if dial-tone first. (I don't
> remember if 3-slots could have dial-tone first). On TV, it seemed
> every pay phone was also pre-pay.

> However, in rural locations, payphones were postpay. That is, you got
> a dial tone and dialed the number. If the line was busy or no answer
> you just hung up. But if answered you had to put in the dime to let
> your transmitter work. On such phones there was no "hold area" for
> coins and associated relay control, coins went directly into the box.
> That meant the phone had a much simpler construction as did the CO
> equipment, making it cheaper. People have previously stated there
> were ways to beat the system with that kind of payphone, but I presume
> the phoneco figured the cost savings were worth the risk, and maybe
> rural people were more honest and less scheming than city people.

Here in the U.K. we've gone from prepay, to postpay, and then back to
prepay again over the years, but they've always been dialtone first.

The "AB" box is fondly remembered by older generations and was
introduced in the mid 1920s. Payphones, or "public call offices" as
they were once called used a modified GPO 300-series desk telephone,
fitted to a wall bracket or shelf and wired to this separate coin box.
The latter had three coin slots on the top, a return chute at the
bottom, and two buttons, one labeled with a very large "A" in a circle
and the other with a large "B" in a rectangle (hence the "AB" name).
This second button was actually located on the side of the box.

The "AB" phone was prepayment with coin collect and return being done
manually by the caller. Dialtone would be heard upon picking up the
phone, but calls could not be dialed until coins had been deposited,
removing a short from the dial contacts. The coin deposit also
applied a short-circuit to the transmitter.

Upon getting an answer, the caller pressed button "A" which collected
the coins and restored the contacts to normal, removing the short on
the transmitter and allowing conversation to take place. If there was
no answer, the line was busy, or the call failed to complete for some
other reason, the caller pressed button "B" which returned the coins
and simultaneously operated a mechanical timer which opened the line
for a few seconds to release any connection. He could also just
hangup for a couple of seconds then try again, leaving the coins in

Extra contacts on the dial allowed zero to be dialed to reach an
operator without depositing any coins (and as the 999 emergency
service came into service the dials were modified to allow a 9 to be
dialed with no coins as well). For long-distance calls, the operator
would listen for the coins being deposited just as on U.S. 3-slot
coinphones, then tell the caller to press button "A" when she got an
answer or to press button "B" to return his money if the call failed
to complete (after the coin deposit the transmitter would be shorted
as on a local call until button "A" was pressed, so the caller was
then unable to speak to the operator).

The "AB" coinphone gradually disappeared from most areas during the
1960s, but a few survived in rural areas much later. I believe the
last one was finally withdrawn from service in a very remote part of
Scotland sometime in the early 1980s

STD -- the British equivalent of DDD -- arrived in 1958, and there was
a desire to allow direct-dial long-distance calls from payphones
without the assistance of an operator. Thus a totally different
design of coinphone was introduced in 1959 and gradually replaced the
old "AB" boxes as STD expanded during the 1960s.

This was a postpayment phone and an integrated design with handset
cradle across the top of the unit, a dial immediately below, and the
coin slots on the right (although a separate coin-box only model was
also produced to use with regular wall-mounted phones which was common
in hotels lobbies and similar semi-private locations).

The old A and B buttons were gone, replaced by signaling from the
central office, and a solenoid-operated shutter across the coin slots
prevented the deposit of coins until the appropriate time.

Calls -- both local and long-distance -- were dialed first, and when
answer supervision was received the office would send a signal to open
the coin shutters while applying "pay tone" to the line, a rapidly
interrupted 400Hz signal at about three times the normal busy-tone
speed (the called party also heard this signal to tell him to wait a
few seconds).

After the initial deposit, the charging equipment would simply allow
the call to continue for whatever period was appropriate based on the
time of day and area called, after which the process would be repeated
with another application of pay-tone to request more money. If the
caller failed to insert more coins within a few seconds, the paytone
would cease and he would be allowed a few more seconds for free to
complete the call, after which it would be disconnected and the
shutters would close again. The paytone soon became known
colloquially as "the pips," e.g. "I'll have to go now, that was the
pips and I have no more change." (On the initial deposit, there was
no such grace period, so it was pay immediately or be disconnected.)

Now all of those postpayment phones I remember so well from the 1970s
are gone too, replaced with modern prepayment types with LCD displays
showing credit left and all the other present-day trimmings. Somehow
to me they just don't have the character or the attraction of that old

Below are links to pictures of the two types I've outlined, first the
AB "kiosk," then the postpayment type. The latter is an older
version, still with lettered dial and slots for 6d. and 1/-. Later
versions had numbered dials only and modified coin mechanisms for the
change to decimal money in 1971.


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