How to Test a Phone Line with a Multimeter?

ToolsBrilliance is reader-supported. We may earn a commission through products purchased using links on this page. Learn more about our affiliate disclosure

A multimeter is a type of electronic instrument that electronic technicians and engineers frequently use. It’s also known as a VOM (volt-ohm-milliampere) and is a multi-measurement electronic measuring device.

They are accessible in both analog and digital configurations and can be used for everything from simple testing like battery voltage measurement to fault detection and complex diagnostics. It is used to measure the three basic electrical characteristics of voltage, current, and resistance. It can also be used to see if two points in a circuit are connected electrically.

Electrical problems in motors, power supplies, appliances, circuits, and wiring systems are diagnosed using them by electricians. Multimeters can also be used to take basic measurements around the house, which DIYers can learn how to do.

Types of Multimeter

  • Digital Multimeter: A measuring instrument, such as a digital multimeter, is the most widely used test equipment in various industries. It improves accuracy by obtaining multiple signal samples in less time. It also includes an automatic ranging feature, which eliminates the need for the operator to select the measurement manually.
  • Autoranging Multimeter: There is a knob in the middle of this type of multimeter, and there are fewer positions. As a result, it is used in simple electronic projects and does not control by design to measure. For electricians and beginners, these tools are highly recommended. Normally, this meter only measures one component at a time.
  • Analog Multimeter: An analog multimeter, also known as a moving coil device, uses a microammeter and a needle to calculate voltage, current, and other parameters. You can easily calculate different quantities by changing the setting of the switch on the meter with the help of several removable probes.
  • Fluke Multimeter: This multimeter is equipped with several features. This meter is used to calculate resistance and voltage and usually comes with a large display. It’s used to change the voltage, current, and electrical unit, among other things.
  • Clamp Multimeter: This multimeter has a clamp feature that calculates amps after the volts from the two probes have been calculated. By multiplying the voltage reading by the amps, you can adjust the power consumption. It also has a bonus feature that allows you to choose from a variety of settings.

Advantages of Multimeter

  • Electrical output can be used to send and receive data from other devices.
  • There is no effect from loading because of the high input impedance.
  • Clear readings can be obtained with longer viewing distances.
  • The output can be presented automatically.
  • It can polarize on its own.          
  • They are less expensive due to the integration of technology.

Disadvantages of Multimeter

  • The meter must be used following the manufacturer’s specifications and the category rating; otherwise, the meter will be damaged, resulting in the loss of equipment.
  • The LCD must be powered by an external source, such as a battery because when the battery is depleted, the LCD becomes dim and difficult to read.

Applications of Multimeter

  • Consistency and resistance testing
    • By determining the frequency and testing the switch, a faulty power cable can be identified.
    • A battery, as well as an outlet, can be tested.
    • It’s used to keep the temperature and environment in check.
    • Diode testing
    • AC/DC Calculation
    • Detection of AC/DC Voltage
    • You can put old incandescent light bulbs to the test.
    • Calculations of time and frequency
    • Power and isolation requirements

How to Test a Phone Line with a Multimeter?


Disconnect everything in the house that is connected to a phone jack. To test them, you’ll need to have the phone lines turned on.


Locate your phone service’s network interface device box, or NID. It’s a large grey box with the words “Telephone Network Interface” printed on it that are usually mounted on one of your house’s exterior walls near your electrical meter by your phone company.

Since your phone lines connect to your phone company’s wiring loop through this box it must be located on or near your property. If you can’t find your NID, call your phone service provider to find out where it is.


Remove the customer access cover from the NID by unscrewing the screws labeled “Customer Access” with a screwdriver. Only the telephone company that installed the NID can remove any screws that aren’t labeled “Customer Access.”


Disconnect the NID test jacks from the phone lines you want to test. The phone lines will be completely open and ready for testing once they have been disconnected. Allow one minute for any electricity in the lines to dissipate while the phone lines are disconnected.


Change the continuity setting on the digital multimeter. These settings are usually indicated by a symbol that resembles a sound wave but consults your device’s documentation for specific instructions.


Connect the leads of the digital multimeter by touching them together. If the multimeter is working properly, it will display a reading on its digital screen and make a beeping noise.


Connect one of the digital multimeter’s leads to one phone wire and the other to another. The phone lines are not touching if the multimeter does not detect any continuity. If it detects continuity, it means the phone lines are touching somewhere and will not work properly.


For each pair of phone lines, repeat the test. You’ll know which phone lines work and which phone lines don’t once each pair has been tested.

Read: How to Test a Fuel Pressure Sensor with a Multimeter?


A multimeter is a tool for checking various aspects of your electrical system. To use a Multimeter to Test a phone line, simply follow the steps outlined above.


  1. Is it possible to test a phone line without a phone?

A multimeter is used to test a phone line that does not have a phone connected to it. If the multimeter is working properly, the reading will appear on the digital screen and a beeping sound will be heard.

2. Is checking an outlet with a multimeter safe?

Before using your multimeter to test an outlet, read the instructions that came with it and avoid touching the metal prongs. You might get electrocuted if you do so. It’s easy to check an outlet’s voltage, and you can also inspect the outlet’s casing to make sure it’s safe.

We will be happy to hear your thoughts

Leave a reply

Tools Brilliance
Enable registration in settings - general