How to test a telephone line with a multimeter

How to test a telephone line with a multimeter

For a telephone line to function properly, it must be an independent circuit that does not come into contact with any other telephone line. If a phone line comes in contact with another phone line, both lines will stop working properly. You can determine if your phone line makes contact by using the "continuity" setting on the digital multimeter on the network interface device mounted on the outside wall of your home.

Step 1

Unplug all appliances in your home that are connected to the phone jack. You will need to open the phone lines to test them.

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Step 2

Locate the network interface device (NID) box for your telephone service. This is a large gray box labeled "Telephone Network Interface" and is usually installed by the telephone company on the outside wall of your house near the electric meter. This box connects your telephone line to the telephone company's line network. Therefore, it should be located near or on your property. If you cannot find your NID, consult your telephone service provider for the exact location.

Step 3 Loosen the marked screw

Using a screwdriver, loosen the screw marked "Customer Access" on the NID customer cover and remove the cover. Any screws not marked "Customer Access" should only be removed by the telephone company that installed the NID.

STEP 4 Disconnect the telephone line to be tested.

Disconnect the phone line to be tested from the NID test port. Once disconnected, the phone line is completely open for testing. Wait one minute with the phone line disconnected before allowing power to flow through the line.

Step 5

Set the digital multimeter to the continuity setting. This setting is usually indicated by a sonic type symbol. However, detailed instructions can be found in the instrument documentation.

STEP 6 Touch the ends of the leads.

Touch the test leads of the digital multimeter. If the multimeter is working properly, a reading will appear on the digital display and a beep will sound.

STEP 7 Connect one of the Multimeter leads.

Connect one lead of the digital multimeter to the phone line and connect the other lead to the other phone line. If the multimeter does not detect continuity, then the phone line is not making contact. If it detects continuity, then the phone line is making contact somewhere and is not functioning properly.

Step 8 Repeat the test for each pair of phone lines.

Repeat the test for each pair of phone lines. Once you have tested each pair, you will know which phone lines are working and which are not.

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A multi-line phone system supports three or more lines.

A multi-line phone system has three or more phone lines. Unlike a typical internal phone that can only hold one line, a multi-line phone can hold three or more lines that can be accessed by pressing a single button. Multi-line phones are most commonly used in businesses, but can also be used in homes. Understanding how to wire a multi-line phone can improve your technical skills and save you some money.

Step 1

Disconnect the modular jack from each telephone line connected to a network interface device, or NID, a plastic junction box installed on your property by your local telephone company. It is usually located on the outside wall of your home or office. The junction box connects the telephone company's incoming line to your internal line and then to your telephone. To find the junction box, follow the phone line from the pole to your property.

Step 2

Feed the CAT-6 cable through the rubber grommet at the bottom of the NID and into the junction box. Strip 5 cm of insulation from the end of the cable with needle-nose pliers. Straighten the bare wires and use a wire stripper to remove 1/2 inch of insulation from each wire.

Step 3

Use a screwdriver to loosen the pair of red and green screws inside the NID. A telephone line needs two wires to work. Therefore, you will need one red and one green termination screw for each incoming wire you wish to connect.

Step 4

Wrap each wire clockwise around the corresponding terminal and tighten each screw. For multi-wire phones with three input wires, for the first wire connect the blue wire with the white stripe to the red terminal screw and the white wire with the blue stripe to the green screw. For the second wire, connect the white wire with the orange stripe to the green screw and the orange wire with the white stripe to the red screw. For the third wire, connect the white wire with the green stripe to the green screw and the green wire with the white stripe to the red screw.

Step 5

Run the CAT-6 cable through your home or office, along the wall closest to where you want to place the multi-line phone. Secure the telephone cable to the power outlet with a cable tie, but avoid running the cable parallel to the power cord.

Step 6

Connect the cable to the power outlet. Measure another meter of wire and cut it into squares. Use diagonal pliers to remove five centimeters of plastic insulation. Straighten the bare wires and use a wire stripper to remove 1/2 inch of insulation from each wire.

Step 7

Loosen the set screw located on the back of the front panel of the RJ-25 connector. Connect each wire to the terminals as follows: for line 1, connect the blue wire with the white stripe to the red terminal screw and the white wire with the blue stripe to the green terminal screw. For line 2, connect the orange wire with white stripe to the yellow terminal screw and the white wire with orange stripe to the black terminal screw. For line 3, connect the green wire with white to the white terminal screw and the white wire with green to the blue terminal screw.

Step 8

Tighten all terminal screws to secure the connections. Secure the connector to the telephone junction box with the screws provided. Go to the NID on the outside of the house and plug in the modular connector to connect to the phone jack on the inside of the house.

Step 9

Connect the multi-line phone to the new RJ-25 jack. Press line 1, listen for dial tone and place a call to test the line. Test the other phone lines in the same way.

How to disconnect a home phone line

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The telephone line consists of two copper wires that run from the telephone company's switchboard to the Network Interface Device (NID), which is attached to the wall outside the house. the NID is a demarcation point where the telephone company's responsibility ends and yours as the user begins. the NID also acts as a terminal where you can connect and disconnect the telephone company's line. Although unusual, you can also disconnect your home phone line.

Step 1

Locate the network interface device (NID) that your telephone service provider has installed on the outside wall of your home. Follow the cable from the NID into the house until you find a telephone junction box, fixture or small plastic box with mounting screws. The cable coming out of the NID goes to the junction box, where it is distributed to all the phone jacks in the house.

Step 2

Unscrew the cover of the junction box and open it with a screwdriver. Grasp the cable coming out of the NID and look at each of the color-coded wires coming out of the cable. Connect each wire to the screw terminals on the junction box.

Step 3 Loosen the screws on the terminals.

Using a screwdriver, disconnect each wire from its terminals by loosening the terminal screws holding each wire. Once all the wires are disconnected, remove the wires from the junction box. Cut the end of each wire with diagonal pliers to remove the exposed copper wire. Wrap the end of each wire with electrical tape. Replace the junction box cover and listen for any noise. If you disconnect the mains power from the junction box, all power or signal to the telephone will be disconnected.

Step 4

If your phone line does not have a junction box, disconnect the power and signal from the phone jack. Use a screwdriver to open the front panel of the outlet. Loosen the red and green set screws on the back of the front panel and remove the wires connected to the screws with needle-nose pliers. Wrap each stripped wire individually with electrical tape. Insert the wires into the telephone socket and secure the front panel of the socket with a screwdriver.