Troubleshooting Your Telephone Service

There was a time when you called your telephone company whenever you had any problem with your telephones and they repaired it for free as part of their services to their customers but those days have gone the way of the 25 cent hotdog. Today, the telephone company's responsibility ends at their Network Interface Device, the NID, the device that connects the company's wiring to the homeowner's wiring. They will still come to your home and fix any problem for you but if the problem is on your side of the NID, expect to pay a stiff service charge. AT&T charges $135 for the first 30 minutes and an additional $30 for each 15 minutes interval there after. You can purchase a service policy from your carrier for a small monthly fee of $2 or $3 which you pay every month. For a yearly fee of $24 to $36 they will come into your home and fix any problem with your telephone system but most customers never use it often enough to make it cost effective.

Residential telephone wiring is so simple that almost anyone can troubleshoot it. By the time you finish these lessons you will not only have the information needed to troubleshoot your own telephone systems you will be able to earn a part-time income by troubleshoot and repair residential systems for friends, neighbors and other people who have neither the skills or the time to do their own work.

Using the Network Interface Device to Isolate the Problem

Where Does the Problem Lie: Telephone Company Wiring or Customer Wiring?

You pick up the telephone receiver and there's no dial tone, where does the problem lie. Does the problem lie with the service provider's wiring or does it lie with the interior wiring system or equipment? The NID should be your starting point when troubleshooting any telephone system problem. It's easily accessible and one five second test will tell you if the problem involves the telephone company's wiring or if it involves the interior wiring that you are responsible for. For a single family residence the NID is usually located outside the home on the exterior wall near the electric meter and should be marked as telephone equipment. In a multifamily dwelling the NID is usually located in the basement or in the individual apartment units.

Once you have located the NID box open the customer access side of the box. There are two access sides to the NID, one marked "Customer Access" and one marked "Telephone Company Access only." always use caution when working with an outside NID. Don't attempt to troubleshoot a problem during inclement weather. Stand on a rubber mat if the ground is wet. A ring tone voltage of close to 100 volts will be present on the line if someone should ring in while you're working on the line. This ring tone voltage could provide you with a potentially fatal shock.

Inside the customer access side of the NID you will find two sets of four screw terminals separated by a raised barrier strip. Each set contains one red, one black, one yellow, and one green terminal screw. Along with each set of screws there will be a short cable that plugs into a matching jack. These plugs and jacks are the same as the plug on your telephones and the jacks they plug into. Unplug these cables inside the NID to isolate the interior wiring from the telephone company's wiring.

Plug a known to be good corded telephone into each of these jacks, if you still have no dial tone, the problem is on the telephone company's side of the NID and it's there responsibility to repair it at no cost to you. If you get a solid, clear dial tone at the NID, the problem lies with the interior wiring or the equipment attached to it and it's your responsibility.

Troubleshooting the Interior Telephone System

Does the Problem Lie with the Wiring or With the Telephones Attached to It?

Reconnect the jumpers in the NID and close up the box. Disconnect everything connected to the interior wiring-corded telephones, cordless telephones, answering machines, computers, FAX machines, Etc. wait fifteen minutes and then check each jack by plugging a known to be good corded telephone into it. If you get a good, solid dial tone at all the jacks, the problem lies with one of the devices that was connected to the wiring system. If you still have no dial tone at one or more of the jacks, the problem lies with those jacks or with the interior wiring.

Good Dial Tone at All Jacks

If after disconnecting every device plugged into the system you get a good dial tone when using the test phone, the problem was caused by one or more of the devices that were plugged into the wiring. One defective device, especially if the defect is an internal short. Since all the phone jacks are on one system anyone shorted device will short out the entire wiring system. To locate the malfunctioning devices, leave the good corded phone plugged into one jack and then plug the remaining devices into their jacks one at a time. Check for a dial tone on the test phone after plugging each device in, if you have lost the dial tone the device that you just plugged in is defective. Remember, you can have more than one defective device on a system so don't assume that all the rest are functioning properly as soon as you found the first bad one

No Dial Tone at One or More Jacks

The problem in this case could be in the actual wire or it could be one or more defective jacks. An open loop caused by a broken conductor isn't unheard of but it is rare that a wire actually breaks. Termites have been known to chew through a telephone wire as have rodents, but they seldom just break. Modern, modular jacks are delicate and are prone to becoming defective and wire do come loose from the jack terminals so always suspect a bad jack or connections at a jack before you suspect the actual station wire. Jacks are interconnected in many different ways. They may be wired using a Star Topography, where each jack has its own wire that runs all the way back to the NID. They may be connected using a Buss topography where they are all connected in parallel on one cable. They may be connected using a combination of the two topologies. The Buss topology is by far the most common.

Testing Modular Jacks

The Sperry Model 3269081 Telephone Line Tester is a relatively inexpensive specialty tool available at most ACE Hardware store and at most major home centers. It's very easy to use, all you do is plug it into a modular jack just as you would a telephone. It has a tri-color (Red-Yellow-Green) LED. No light indicates a dead line. A green light indicates the line is functioning properly. A red light indicates a line with reversed polarity. A yellow light indicates the presence of an AC voltage on the line which is often the cause of a noisy line. No light tells us that we have a dead line but it doesn't tell us if the dead line is caused by the actual wiring or by the modular jack itself.

To be able to use the Sperry Telephone Line Tester to check the actual wiring we need to make a simple test adapter using a modular wall jack and two test leads, one red and one black, with alligator clips on one end. Attach the red lead to the red wire on the modular jack and the black one to the green wire. To test the actual wiring remove the cover to the jack in question and clip the test leads to the red and green wires/screws. If the Line Tester plugged into the test adapter lights up green, the wall jack is bad. If it remains dark, the wall jack isn't the problem, he problem is with the wiring itself.

If you have a number of dead wall jacks on a Buss topology, suspect a bad connection at the last wall jack where you have a good dial tone.

Locating a Broken Wire Inside a Wall

Once you have determined that you do have an actual broken wire inside the wall, the easiest way to locate where it's broken is to use a tone generator and tracer probe set like the Ideal 33-864 set. This is pricey test set but what it saves you in time will more than justify it cost. The easiest way to use this test set is to plug the modular cord into a known good jack and then run the probe along the suspected route of the wire until you lose the signal tone. When that happens you have found the break in the wiring. Before using this test set make sure to isolate the interior wiring from the telephone company's wiring at the NID by unplugging the modular jumpers. You don't want to send your test tone out over the telephone company's wires.

You can repair a broken wire in the wall in one of two ways. Single line systems use the red and green pair, try using the yellow and black pair as a substitute. If they still have continuity, you have solved your problem. If that pair is broken also, then your best bet is to bridge that section with a new run of wire. Opening up the wall to splice the broken wire is always a hit and miss proposition because it could be broken at more than one spot. Running a new wire from the last working jack to the first jack after the break is the quickest and easiest repair possible.