[VoIP] 4-Wire Telephones?

[David Josephson]

Rusty Dekema wrote:
> On 3/16/07, John R. Covert <john_reads_cnet_via_archives at covert.org> wrote:
>   
>> I assume you're referring to the standard four-prong pre-modular
>> phone jack: http://www6.covert.org/4-prong.jpg
>>
>> These had nothing to do with four-wire phones.  Just like a modern
>> modular RJ-11 jack, which is also a four-wire (and occasionally
>> 6-wire) jack, the old 4-prong jacks were used with two-wire phones.
>>
>> Tip and ring were wired to the two pins that are farther apart.
>>
>> I'm sure your grandmother's house did not have four-wire phones.
>>     
>
> Ahh, interesting. Those are the connectors I was referring to. I am
> wondering why 4-prong connectors and 4-wire wiring were used to wire
> houses in the "old days" (pre-1940). Was it for future expansion in
>   
And of course, the main reason for extra wires that I omitted from my 
last, is to provide ground for tip-side or ring-side ringing, the party 
line ringing schemes that probably lasted the longest into the dial era.
> case subscribers wanted multiple lines? I could be wrong, but I
> thought that such service would have been extremely rare in those
> days. But maybe the phone company was just forward thinking :).
>
> So, my grandmother's house aside, was the PSTN ever a 4-wire system? I
>   
Not that I'm aware of, ever, anywhere.

--
David
> really thought it was, but I could definitely be mistaken. If 4-wire
> phones were used on the PSTN at one point, about when was this
> practice discontinued?
>
> Thanks,
> Rusty
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