TELECOM Digest OnLine - Sorted: Re: Party Line Dialing, was Re: Telephone Area Codes and Prefixes

Re: Party Line Dialing, was Re: Telephone Area Codes and Prefixes

John McHarry (jmcharry@comcast.net)
Sun, 18 Feb 2007 02:27:36 GMT

On Fri, 16 Feb 2007 07:38:25 -0800, hancock4 wrote:

> In cities, if you had a party line (2 or 4 party) you had a listed
> number the same as anyone else. If someone called you, they dialed
> the listed number normally and only your phone rang. The Bell System
> used a special wiring technique to isolated the ringers of up to four
> separate parties so only the desired party would ring. (I believe it
> was a combination of bias and grounding). The independent companies
> used different ringer frequencies to isolate ringers.

Bell used diodes and grounded ringing to get four party full selective
ringing. This gave plus and minus tip parties and plus and minus ring
parties. REA standard companies used one of a series of frequency
selective ringing schemes to put up to five parties on tip and five
more on ring. I have no idea how common such large agglomerations
were.

> Note -- the above is for party lines of up to 4 customers. I believe
> anything beyond 4 had to be on a manual system and had to use special
> short-long ringing codes. Everybody heard the other phones ringing
> and had to listen if it was their code.

Frequency selective could go beyond four, as noted. I don't recall
either scheme being able to effect ANI beyond two party, so outgoing
calls had to use operator number identification, which led to the
jocularly named "no test trunk". The operator would dial the number
given to see if the result bridged onto the correct line.

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