TELECOM Digest OnLine - Sorted: Re: Old Party-Line Arrangements

Re: Old Party-Line Arrangements

Paul Coxwell (
Wed, 9 Feb 2005 00:10:32 -0000

Many thanks to all who have replied. The variety that existed in the
old U.S. network makes for some interesting history compared to the
British situation where the nationalized GPO (General Post Office) ran
all but a couple of tiny independent companies and practices were
pretty much standard right across the country.

> Only on manual exchanges where you saw a lot of numbers like 1234J, or
> it was just spelled out, e.g. my mother's phone number in Bell
> territory in Vermont in the 1930s and 40s was six two ring three.

Now I think about it, I've seen something like that on an old postcard
from the 1950s (I think it was from a rural motel). The number shown
was 421R2, or something similar to that, so presumably that's "ring 2"
on the end.

> In the 1970s, I knew people at non-Bell independents who used circle
> digits, the extra digit to identify the calling phone. There was also
> a surprising amount of ONI, operators cutting in to ask for your
> number, even on private lines in Bell territory before ANI was
> universal.

Why the name "circle" digit?

> included a small 3-transistor amp from a defunct tape recorder attached
> to the line, so I could listen to party-line conversations without going
> offhook. As most other eavesdroppers have probably found, 95% of the
> conversations were extremely boring.

I guess eavesdropping was a pretty widespread pasttime. In fact back
about 25 years ago my parents were on a party line and I lashed up a
similar arrangement to monitor calls. My amp was a home-brew kit
using, if I recall correctly, EF80 and ECL80 tubes.

> The letter usually used in manual exchanges were J and W on two party,
> with R and M added on four-party. (Lines with more than four parties
> had other conventions.)

Is there any particular significance to the letters? Can anyone
remember which letters were which combination of tip/ring and
polarity/cadence, or is that going back a little too far?

> In the Bell System, ground start was never used for residential
> service. On two-party lines, the "tip" party would be wired with the
> ringer (and, on occasion, a portion of the hybrid coil) connected
> between the tip lead and ground, without an isolating capacitor, to
> allow the CO to determine the billing party. If there was current flow
> to ground, then the "tip" party was making the call.

The wiring arrangements adopted by the GPO here meant that every phone
intended for party-line use could be sent out into the field wired the
same way. The switch had changeover contacts and was inserted into
the "A" wire (GPO terminology for what would normally be the tip side
of the line) so that when pressed it opened the loop and grounded the
"B" wire (normally the ring side of the line) via the hybrid and
remaining circuitry. The bell would then be wired from the "B" wire
to ground.

The two stations were designated X and Y. The X subscriber's set was
wired the normal way, A to tip, B to ring, then all that was necessary
when installing at the Y subscriber's premises was to swap A and B at
the junction box. Thus X had ringing on ring and grounded ring for
dialtone, while Y had ringing on tip and grounded the tip to originate
a call.

In SxS offices (which formed the majority of exchanges here for many
years) there was a small relay set which then simply switched the line
to the appropriate uniselector or linefinder on detecting the
ground-start. Incoming calls were what you all describe as
terminal-per-station and could come from completely separate final
selectors (connectors) for each party, thus giving complete freedom on
which two numbers would share the line.

Party lines certainly survived in some areas quite a way into the
1980s. There are still shortages of pairs in some places these days,
except now BT makes extensive use of DACS units to multiplex lines.



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