I'm interested in getting some more detailed historical information on
the way party-lines were arranged years ago.
Here in Britain with our relatively small area and comparatively high
density of population, a two-way line was the norm with ringing
applied to tip or ring and bells connected from one side of the line
to a local ground. Outgoing calls used a ground-start method, with
subscribers having to press a button to obtain dialtone. (As even
local calls were charged, this method enabled the C.O. to determine
the originating party at the outset.)
I've gleaned from various sources, including some old Digest posts,
that in the U.S. there were various methods employed, including up to
10-way party lines with the last digit of the number selecting tip or
ring and the appropriate ringing cadence. I've also seen references
to tuned ringers with ringing applied at a different frequency for
each party, and to party-line numbers having an additional digit
(coded as a letter) added the end of the regular number.
When it comes to outgoing calls once DDD and CAMA had arrived, I've
seen references to different ringer wiring combinations to enable the
equipment to test for originating party, and also in the earlier days
of DDD that in some places (maybe small independents?) callers had to
dial an ID digit (e.g. 1x + NPA + number).
Can anybody elaborate and explain in more detail the arrangements
which were commonly used, both in the Bell System and in the larger
independents?
Thanks,
Paul
Paul Coxwell (