Your Connection Point: The Network Interface Device (NID)
The Network Interface Device (NID) is a phone company installed device
that connects your inside wiring to the telephone network. It is a gray box outside your house, probably mounted near
the electrical meter. It contains a modular plug that allows you to disconnect all inside wiring and connect a working
phone to test whether the local exchange network is working. The NID has two "sides" - one for the phone company
and one for you, "the customer access" side. You should not attempt to enter the phone company side of the NID. All
of the wiring you need to do is completed on the customer side of the NID. In some older installations, you may not
have a NID. Instead, you will find a "protector block", a small plastic covered box where the cable coming out of your
house connects to the phone company's cable leaving your house. The protector block serves the same purpose as
the NID, but does not provide a modular jack where you can check if you are getting dial tone from the phone company.
If a phone company technician comes to your home on a service call, a NID will be installed at no charge to you, if
time permits. If you do not have a NID, one should be installed when you have a second line connected.
The information provided below is generic in nature.
Consult the label inside your NID and adjust to your particular installation as required.
Testing Your Phone Service at the NID
- Unscrew the Network Interface cover at the Customer Access point with a screwdriver and open.
- Disconnect modular plug from test jack. If you have more than one line, select the test jack for the line that is
causing the problem. This disconnects your inside wiring from phone company's line.
- Wait one (1) minute, then insert plug from a telephone set you know is working. You are now plugged directly into
the phone company line.
- Try the telephone.
- If problem still exists, it is in phone company's lines. Contact your phone company repair
service. If problem is gone, you have trouble on your inside wiring, equipment, jacks or remaining telephone sets.
Contact your phone company, a contractor or someone else, or make the repairs yourself.
- Once you have finished your test, disconnect your testing telephone and securely re-insert the original modular
plug. Close the cover and screw the fastener down until the cover is snug and tight.
The wiring bridge modules in your NID may have two screw posts, as shown in the top of the diagram at the right ,
or four, as shown in the bottom of the diagram. If your wiring bridge modules have two screw posts, each line
will appear on a separate module. If your wiring bridge modules has four screw posts, line 2 may appear on the black
and yellow screw posts of the same module as line 1 (and as line 2 on the test jack of that module) or on the green and
red screw posts of a separate module. Consult the labels inside your NID to determine how your lines are connected.
To install or replace your inside wiring at the Network Interface Device
- Open customer access side of the NID.
- Disconnect modular plug from test jack. This disconnects your inside wiring from the phone company's lines.
- Using a pen or pencil, punch a hole through the grommet and pass the wire through the hole in the grommet (punch
one hole for each wire). Pass the wire behind the hinge pin as shown in the diagram at the right.
- Loosen the screw posts on the customer wiring bridge one full turn.
- Strip off one half inch of insulation from each wire and connect them to the color corresponding screw post, wrapping
each clockwise between the washers on the screw. Tuck excess wire in wiring trough. Tighten screws securely.
- Re-insert modular plug into test jack. Close the cover and screw the fastener down until the cover is
snug and tight.
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