[VoIP] 4-Wire Telephones?

[Doug Alderdice]

At 03:49 PM 3/16/2007 -0400, Rusty Dekema wrote:
>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
>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 :).

Hardly.  The four-prong plugs and jacks of old date to the days of separate 
subsets and desk stands in the house.  You could, for an extra charge of 
course, have jacks wired to your subset such that you could move the desk 
stand to another location in the house.  The wiring between a subset and an 
anti-sidetone desk stand requires four wires.  Also, by making subset 
stationary, the ringer is never disabled by leaving the desk stand 
unplugged, as the ringer is mounted in the subset.  In the era that these 
plugs and jacks date from, a home with more than one phone line was 
completely unthinkable; most homes had party lines.

When the use of the four-prong plugs and jacks evolved from subset wiring 
to a direct line connection, I don't know, but I assume it was with the 
introduction of the WE 302.

>So, my grandmother's house aside, was the PSTN ever a 4-wire system?

Very early Strowger switches (c. 1900) had more than two wires but I don't 
know the details offhand.  Bell System lines have always been two wires 
(plus a ground for party line ringing), AFAIK.

Doug.