Landline telephones receive power and signals via two copper wires that run from the telephone company central office to the network interface device located just outside your home. A landline telephone is the basic form of residential and small business service connection to the worldwide telephone network. Landline telephones are designed to render many years of service, but abuse and misuse coupled with wear and tear can cause a landline telephone to break down. Learn to troubleshoot a landline telephone and avoid calling a telephone repairman.
Locate the network interface device, or NID, and open the NID cover with a screwdriver. The NID is a small plastic box (coloured grey or tan) typically mounted by the phone company on a wall just outside your home. Find the short wire beside the green and red terminal screws inside, and unplug the wire from its jack to disconnect power and signals from the phone company.
Get a working telephone and plug the phone into the jack mentioned in step 1. Lift the handset and listen for a dial tone. The presence of a dial tone indicates that the line from the telephone company is working, and that the problem is with your household wiring. The absence of a dial tone indicates that the problem lies with the telephone company line and not within your wiring. Call the telephone company to report the problem if there is no dial tone, and wait for the phone company to fix the line.
Unplug each telephone inside your home from its jack. Plug each phone into the jack mentioned in step 1, and listen for a dial tone. The absence of a dial tone indicates that the plugged telephone is defective and should be checked. Troubleshoot the defective phone by performing the procedures in step 4.
Hold the cord that connects the handset to the telephone base of the defective phone, and unplug it at both ends. Unplug a similar cord from a working telephone, and plug it to the handset and base of the defective telephone. Plug the telephone to the NID jack and check for a dial tone. The presence of a dial tone indicates that the problem lies with the cord you just replaced. Buy a similar cord, install it and check the telephone once more for a dial tone.
Hold the patch cord of the defective telephone and unplug it from its jack at the bottom or side of the telephone set. Get a patch cord from a working telephone, and plug it into the defective telephone. Plug the telephone into the NID jack and listen for a dial tone. The presence of a dial tone indicates that the problem lies with the patch cord you just replaced. Buy a similar patch cord, install it and test the telephone again for a dial tone.
Inspect the defective telephone for any obvious signs of damage, such as a cracked plastic casing, cracked handset or burnt odour. A telephone is a complicated piece of electronic equipment, and no user-serviceable parts are inside it. Unless you are an electronics technician, you are better off replacing the unit. Call the telephone company to request a replacement phone if it supplied the telephone, call the manufacturer if it is under warranty or buy a new one if the unit is no longer covered by a warranty.
Replug the wire into the jack inside the NID to allow power and signals to flow inside your household telephone wiring, and plug a working telephone into a jack. Unplug any device connected to your phone line, such as a security alarm, modem, fax machine, VOIP adaptor, caller ID device and other telephones, one at a time. Listen for a dial tone each time you unplug a device. The presence of a dial tone after a device is unplugged indicates that the device you just unplugged is causing the problem. Do not replug the device, but have it fixed.
Unplug anything that is plugged to your phone line. Get a working phone, plug it into each jack inside your home and listen for a dial tone each time you plug the phone into a jack. The presence of a dial tone in one or more jacks, accompanied by the absence of a dial tone in another jack, indicates that the jack without a dial tone is defective. Troubleshoot the jack by following the procedures in step 9.
Unplug the short wire inside the NID. Unscrew the faceplate of the wall jack using a screwdriver, and pull the plate away from the outlet box. Trim the wires or bend them away from each other with diagonal pliers if any wires are coming in contact with another. Tighten any loose connections with a screwdriver. Look inside the jack's opening and align any bent or misaligned copper pin using needle nosed pliers. Replace the jack if any pins or wires are severely burnt or damaged.