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PAT - DO NOT display my email address anywhere in this post! Thanks.
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bv124@aol.com wrote:
> Back in the late '60's and early '70's, in Carbondale, IL (GTE),
> we had what was called "suburban" service as we were fifty (50)
> feet outside the city limits. This was a ten (10) party line
> where each line rang uniquely (no coded ringing.) When you dialed
> a toll call (1+), an operator came on the line and asked for the
> number you were calling from for billing purposes!
> I think it was a SxS office.
This type of party line ringing was called "frequency selective" or
"harmonic" ringing.
Most telcos, especially Bell, have used a standard of 20 Hz for
ringing a phone line. However, by using up to five different
frequencies for ringing each party on the same side of a multi-party
line, you could individually ring the desired party without disturbing
any of the others.
Also, most party line systems split the line set-up in two "halves".
One side of the party line customers have their phones wired "tip to
ground", while the other side of the parties have their phones wired
"ring to ground".
Regardless of the switching equipment (manual, SXS, Panel, XB, ESS,
even digital), you can have fully selective ringing on a 2-party line
since one party is the "ring to ground" while the other party is the
"tip to ground".
Bell telcos rarely if ever used harmonic or tuned or frequency
ringers. Independent telcos have regularly used them, especially on
party line systems of more than 2 or 4 parties, since they frequently
set up 10 or even 20 parties on a line in rural areas.
It was also possible to have fully selective ringing on a 4-party
system by adding "biased" ringing -- i.e., positive bias as well as
negative bias, in addition to the tip vs. ring to ground.
Thus, you could also have an 8-party system where only two parties at
a time would ever hear their bells ring, since you'd only double the
number of parties on a fully selective 4-party system. There would be
coded ringing in addition to the "bias" as well as the "tip vs. ring
to ground". The most common ringing code sets were single ling rings
and double short rings. But there have been others.
Some manual systems had machine controlled ringing. The operator
simply plugged into the desired party and the ringing was controlled
automatically. But in other manual systems, especially magneto, the
operator either pressed a ringing button, or turned a crank (magnet),
and thus could produce almost any combination of possible ringing
patterns.
Most telcos these days have discontinued party line systems, although
some might have grandfathered long time customers under the lower
party line rate. However, in today's environment, since telco does not
own the customer equipment anymore, it is difficult for telco to make
certain that the phones are wired the right way for that particular
party. Sometimes the phone company can do the special wiring trick at
the demarc box outside the house, thus the customer can have several
"standard" wired phones in their house. And with today's plasic
electronic phones, it might be impossible for telco to open up that
piece of sh** to "re-wire" the phone itself for that particular party
line customer.
Anthony Bellanga (anthonybellanga@notchur.biz)