If your intent is to totally disconnect from your local phone company, you need to isolate your inside wiring from the line (or lines, if there are more than one) feeding your home, that come from the telephone company central office (a telephone company line is sometimes referred to as a "PSTN line" - PSTN is an acronym for "Public Switched Telephone Network"). You need to disconnect the line even if it appears to be dead, because at some point the phone company could place voltage across that line for one reason or another, and that could damage your equipment, and even possibly start a fire! So here is how to isolate your inside wiring from the telephone company's line.

On the outside of your home, you should find a telephone company Network Interface Unit. This is the demarcation point between your wiring and the telephone company's wiring. It may not look exactly like the one in the picture at the left, but you will know it because the telephone cable coming to your home from the street, as well as one or more lines from inside your home will go into it. When you open it (usually by undoing a single common screw), you will be able to access the wires going into your home, but not the ones coming from the street. This is by design. There should also be a ground wire coming out of the telephone company's side of the box. It is important to leave the ground wire connected, since it can help guard against lightning damage to your home (in the event that lightning strikes a nearby phone cable).

Note: There may be a few older homes that still have an old-style telephone company lighting protector (such as the one pictured at the right, which has the cover removed) on the outside of the home (or sometimes it was placed inside the home, at the point where the outside telephone wiring came into the home). It's rather rare to come across that situation, since almost all of those older protectors were replaced with the newer style Network Interface Units years ago. An even less common situation is to find the protector, or possibly a Network Interface Unit mounted on a pole at some distance from the home. These instructions aren't really intended to address those types of situations, although if you have a basic understanding of good telephone wiring practices and you read through these instructions, you may be able to figure out what needs to be done. The section below entitled "What about those old lightning protectors?" will cover this in more detail.

Once inside the Network Interface Box, you should see one or more sets of screw terminals (two or four screw terminals per line) and short stubs of wire with a standard telephone plug on the end, plugged into a matching jack as shown here (if you don't see the wire stub and plug, you may have a "plugless" Network Interface Unit - in that case, see the section below entitled "New advice for a new kind of Network Interface Unit"). If there is only one line coming into your home, there will probably only be one plug and set of screw terminals. Now, assuming that you are the sole occupant of your home, it should be sufficient to simply unplug all the plugs. Unfortunately, that leaves too much opportunity for Murphy's Law ("anything that can go wrong, will") to come into play. In this case, what can go wrong is a telephone company employee going to the wrong home (yours), finding the plug unplugged, and plugging it back in.

Note: The above photo shows part of a brand new Network Interface Box with no wiring installed. Your box will have one or more pairs of wires attached to the screws adjacent to the plug(s). If the screws next to a particular plug have no wires attached, then unplugging that plug will be ineffective, since no inside wiring is connected to that plug. If you open a box and see only screw terminals with no wires attached, STOP - something isn't right (it is not uncommon for there to be four screws next to a plug but only two of them are wired, however if none of them are wired, then that plug is not being used with any inside wiring). Unplugging a plug next to totally unconnected screw terminals will NOT break the connection to the phone company's wiring. Also, we again remind you that these instructions are not intended to cover situations where there are multiple lines involved, such as the network interface box shown at the right. You might encounter this type of box on the side of a condominium, apartment building, or other multi-family situation, or in a home where there were once multiple lines installed (a home that was once used for business purposes, or possibly a telemarketing operation). There is simply no way we can tell you which wire(s) would be the proper one(s) to disconnect in a situation like this, and if you disconnect the wrong wires, you might interrupt service to a neighbor (in a multi-family situation). Even if you see a plug (as shown in the photo), unplugging it may not disconnect the wires you really need to disconnect.

You don't want to remove the interface because someday you might sell your home, and the next person to come along may want phone service. So, here is what we suggest. PLEASE READ THE FOLLOWING TWO PARAGRAPHS CAREFULLY, THEY ARE QUITE POSSIBLY THE MOST IMPORTANT ON THIS PAGE:

First, unplug all the plugs and take some black plastic electrical tape (or any other vinyl tape you may have) and wrap the ends of the plugs, so that they cannot be plugged back in without removing the tape. Then, take a stiff piece of cardboard (preferably white) and cut it so it will just fit inside the box when you close the lid. In waterproof ink (some felt-tip ink and most bubble-jet printer ink is NOT waterproof), write something like this in bold letters on the cardboard: "ATTENTION TELEPHONE COMPANY: DO NOT RECONNECT THESE CIRCUITS — WILL DAMAGE EQUIPMENT INSIDE!" Shut the lid on the box and screw it down. Then take a label and write the same message and tape it to the outside of the lid using clear waterproof tape. Why? Well, in case you hadn't noticed, these are "trick" boxes. The phone company can open their side AND your side in such a way that the cardboard might stay in the lid. So by putting the message both inside and outside the box, you reduce the chance that it won't be seen.

An even better idea is to use a small hang tag with string (like the tags that some auto repair shops attach to your keys while you have your car in for service). You can write your message on one of those and tie it right to the plug.

Another thing you can do, although you shouldn't need to if you have taped the plugs and left a message inside the box, is to physically disconnect the wires from underneath the screw terminals. But if you do that, you need to tape the ends of the wires (or dip the ends into a tube of silicone caulk and let them dry) so they cannot short out against each other — or anything else — inside the box (Note: Use electrical tape only to insulate individual wires so they do not touch each other, and only when in a dry location - never use tape to connect two or more wires!). Also, don't do this if there is more than one set of inside wires connected to the screw terminals — in other words, if you see more than one wire connected underneath a single screw, then leave the wires alone — otherwise, you'll most likely break the connection between the phone jacks inside your home, which is exactly what you don't want to do (there is one exception to this advice, and that is when you encounter one of the new "plugless" Network Interface Units — see the next section). Just unplug and tape and tag the plug, as mentioned above.

One other thing you can do is to wrap a long nylon tie-wrap completely around the box so that the box cannot be opened without cutting the tie-wrap. In other words, anything you can do to give a phone company employee second thoughts about opening the box and/or reconnecting the plug can't hurt.

In the past I have said that if you ever sell your home, please remember to reverse what you have done, so the new owner doesn't have to pay the phone company some outrageous sum to come out and take the tape off of your plug (note that if the tape has left sticky residue on the plug, you might want to clean the plug with a little WD-40 on a rag to remove the adhesive, followed by denatured alcohol to remove the WD-40! And, for goodness sake, LET THE ALCOHOL DRY COMPLETELY before you plug the plug back into the jack — alcohol and sparks are an explosive combination!). While this is still good advice, it's becoming more the case that people are using VoIP or wireless instead of getting landlines, so you may want to ask the buyer of your home if they ever intend to get landline phone service and if not, just show them what you've done so they know how to reverse it should the need arise.