Actually, the standard telecom voltage has been 48 vdc,
With two interesting triviata.
The term "Ring" refers to the ring of a plug that is the direct ancestor of what we use for musical instruments today
So "Tip" refers to the TIP of that same plug.
The other odd details of note are that in the original "Bell System" most phone wiring for POTS was on either Red Green Yellow 3w cable or Red Green Yellow Black 4c wire.
The oldest connections used Red and Green for the talk and dial circuit and the Yellow was often used for either Ringing or party line user identification -where the GREEN wire was POSITIVE and called TIP.
The RED wire was Negative and called Ring
The Yellow wire was called SLEEVE or the rearmost part of the plug with BLACK as a second sleeve in my recall of the systems. Curiously when I fact checked myself the Yellow wire use seemed to be regional and not totally consistent even in the same region..
Oren Beck
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