Telephone Jacks
and Wiring

Instructions for Installing
telephone wires and jacks.

Telephone Jack Wiring

How to wire a telephone jack.

Wiring a
Telephone Jack

Telephone Jack

The above picture shows the
back side of a common
telephone jack used today in
the home and business.

The telephone jack has six
colored wires, green, red,
yellow, black, white, and blue.

For a single telephone number
only the green and red jack
wires are used.

If there is a second telephone
number added onto a jack
for a two line telephone, it is
connected to the yellow and
black jack wires.

If the jack wires has a white
and blue wire, they are used for
special applications.

Telephone Wire
Colors Codes

Older Three Conductor Wires

Red - (Ring) - first line

Green - (Tip) -first line

Yellow - was used for ground
in a multi-party line setup

Older Two Pair
Conductor Wires

Green -(tip) - first line

Red - (ring) - first line

Yellow - (tip) - second line

Black - (ring - second line

Four Pair Conductor

White with blue marks (tip)
- first line
Blue with white marks (Ring)
- first line

White with orange marks (tip)
- second line

Orange with white marks
(ring) - second line
Usually designated for ADSL,
if no second line is used.

White with green marks (tip)
- third line
Green with white marks(ring)
- third line
Usually designated a spare,
or for a fax line

White with brown marks,
Brown with white marks,

Dual Telephone

The dual line jack is used
where two separate telephone
numbers are required at one
telephone jack.

Each separate telephone line
is attached to the red and
green wires of each
separate jack outlet.

The white/blue wire of the
set run wire connects to
the green wire of one side
of the dual jack.

The blue wire of the set run
connects to the red wire of
the jack.

The white/orange wire of the
set run connects to the green
wire of the other side of the
dual jack.
The orange wire connects
to the red wire.

This jack is wired to have two
separate telephone numbers
at the dual jack.

To have both sides of a dual
jack have the same telephone
number, bridge with a short
jumper wire, one half of the
dual jack to the other.

Green to green, and red to red.
Connect the w/b of the set
run to the green of one of the
jacks, then connect the blue
wire of the set run to the red
of the same jack.

Both sides of the jack will now
work with the same telephone
Sometimes this is done to use
half the dual jack for an
answering device.


No matter what kind of jack,
all the jack wiring is the same,
center two pins are telephone
line one.

and Repair

90% of telephone noise occur
at the telephone jack and

Unplug the telephone set cord
from the wall jack and check
the telephone set wire plug
end for corrosion (discoloration).

The tiny pins should be shiny
clean gold in color, any green or
black indicates corrosion.

If there is corrosion, both the
set cord and wall jack need to
be replaced.

Telephone surface mounted
jacks are located low on the
wall where they are susceptible
to water damage when rugs
are steam cleaned,
the water-soap over spray ends
can up in the telephone jack.

Also wall washing can cause
water/soap to end up in the jack
causing corrosion.

The worst cause of telephone
jack corrosion is caused when
people hang wall paper, the
water and glue mixture is
extremely damaging, because
the conductivity of the glue
is very high, causing corrosion
in a very short period of time.

Static on The Line

Pick up the receiver on your
telephone and dial any single digit,
other than zero.

This remove the dial tone.

While listening in the handset
receiver, wiggle the set cord near
the telephone jack and at the

If there is a poor connection,
you will hear static.
Also wiggle the handset cord
at both ends of the handset cord,
while listening for static.
If you can hear static while
wiggling the cord, the set cord
needs to be replaced.

Loose connections and corrosion
causes static in telephones.

Remove the telephone jack cover,
and check that the wires are
tightened down firmly.


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and Repair,
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