Telephone wiring question?

Question

there are four wires in the junction box,red green yellow ,and black.the yellow and blackwires aren't connected to anything,so what are they there for?

Answer 1

The red and green wires are the ones used for the phone signal.

In the old days, the yellow and black wires were sometimes used to power the light in the phone's dial. They also did something with the yellow wire when you had a "party" line (line that was shared with other users).

Now days, the yellow and black wires are spares and can be used if you want a second line.

Edited in response to Joe R:

You are correct in that the older telephones used a drop cable that had only one pair. This would have been connected to the Red/Green pair of the quad station wiring that went to the phones.

However, if the phones being used had dial lamps, a plug-in transformer would have been installed somewhere in the house and connected to the Yellow/Black pair of the station wiring. This was used to power the lamps. I believe that some party line arrangements also required that the Yellow be connected to earth ground. (the ground rod outside the house).

Answer 2

ok.. so if the first 2 answers are right, then answer me this... why are OLD drop wires only 1 pair??? if there answer about old phones using both pairs of the i/w was accurate, then old drop wires would have atleast 2 pair, but they DONT!!!

green/red is for line 1
yellow/black is for line 2, or as a spare if the green/red becomes defective....

your wire is out of date, the green/red/yellow/black colors have been replaced with the indtoduction of CAT 3 and CAT 5 wiring...

CAT 3 or 5:
blue/white -> green (line 1 tip)
solid blue -> red (line 1 ring)
orange/white ->yellow (line 2 tip )
solid orange ->black (line 2 ring )

this is the most you will normallay see at a residential 6 pair NID: (CAT 3 can be 2 pair, 3 pair, or 4 pair, CAT 5 is 4 pair)

blue/white + solid blue = line 1
orange/white + solid orange = line 2
green/white + solid green = line 3
brown/white + solid brown = line 4
slate/white + solid slate = line 5
blue/red + red/blue =line 6

Answer 3

older phone systems used to need all 4 wires, but now days only 2 are needed. the extra 2 can be used for a second line in the house if you had a need.

Answer 4

I was gonna answer, but Hillbilly and Silva said it all! :D

What hillbilly said was what came first, then what Silva said came second, and now the other 2 wires are not needed, and some people use them if they get a second line in.

~Cindy! :)

Answer 5

If you don't know what their for and your phone works fine, then don't mess with the wires.