Telephone Jacks
and Wiring

Instructions for
Installing telephone
wires and jacks.


Telephone Jack
standard 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

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
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 number.
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 telephone.

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
and soap over spray ends
can up in the telephone jack.

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

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 telephone.

If there is a poor
connection, you will hear
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

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


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Telephone Jack Wiring
and Repair,
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