Phone System Basics
The phone company owns and maintains the telephone lines (wires) that bring phone service to your house. The lines usually connect to the house at a gray plastic box mounted to an outside wall. This box is called the NID (Network Interface Device). Inside the box, the connections may split into two parts, the utility (phone company) side, and the customer side. Although you can access the customer side of the box, the phone company side has a special screw that’s designed to be difficult to remove; it’s best to leave this side alone. The NID is the standard demarcation point.
Inside the House
Beyond the demarcation point, the phone wiring may lead to a junction box that serves as a switchboard for multiple lines running throughout the house. Each line may lead to one or more phone jacks. If there is a problem on one phone and not the others, examine this phone’s jack and line back to the junction box. Older phone systems may have a single line that connects to all of the jacks in the house. If this one line is damaged at any point, all of the phones may be affected. With either setup, any of the lines can be split en route to any jack so you may find splitters or mini junction boxes between a jack and the main junction box or the demarcation box.
Locating the Trouble
First, you need to know where the problem lies. Start at the demarcation point (NID) or the customer side of the exterior telephone junction box. Try plugging your telephone into one of the phone jacks in the junction box. If there is service (a dial tone) that sounds normal, the problem lies somewhere inside the home. If you have noise on the line, dead air, or a buzzing sound, it’s the phone company’s problem to fix. At that point, simply call the phone company for repairs. If not, read on.
