[Coco] Coco Modem phone line connection

Dave Philipsen dave at davebiz.com
Mon Dec 2 16:08:00 EST 2019


From https://en.m.wikipedia.org/wiki/Telephone_plug:

Though four wires are typically used in U.S. phone cabling, only two are necessary for telecommunication. In the event that a second line is needed, the other two are used. They are also sometimes used to provide power for telephone dial lamps (6 volts AC, as in the Princess phone), or other features.


Dave

> On Dec 2, 2019, at 2:55 PM, Bill Gunshannon <bill.gunshannon at hotmail.com> wrote:
> 
> On 12/2/19 3:38 PM, Dave Philipsen wrote:
>> 
>> The original question from Rietveld had to do with whether two-way modem 
>> communication is achieved over the same pair of wires on the telephone 
>> line (most homes are wired with two pairs). 
> 
> Actually, most homes have only a single pair of wires coming in
> from the pole.  In the good ole' days the second pair would be
> used to provide power for the light in that cure Princess phone.
> Even homes with multiple phone lines (like mine used to be) only
> has single pairs run from the pole and terminated in the basement.
> If you had multiple line phones using a 4 wire RJ11 the pairs were
> combined in the basement where they come in.
> 
> bill
> 
> 
> 
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