How to repair a cordless phone base unit

Updated February 21, 2017

A cordless phone has a wireless handset that sends and receives radio signals to and from a base unit that is wired to a phone line. Except for the cordless handset, cordless phones are the same as any other landline phone. Cordless phones allow you mobility and comfort but can sometimes break down and cause you a lot of inconvenience. Learn how to troubleshoot or repair a cordless phone's base unit and handset before replacing them, and save yourself some cash.

Look for the network interface device, or NID, attached by the telephone service provider onto a wall nearest to the telephone company telegraph pole. Unscrew the holding screw in front of the cover using a screwdriver. Open the cover and look for a short wire with a modular plug (similar to the plug at the end of your landline phone patch cord) and unplug the modular plug from its jack.

Get a working corded landline phone and insert the modular plug at the end of its patch cord into the jack inside the NID. Lift its handset and listen for a dial tone. The absence of a dial tone indicates that the problem lies inside or beyond the NID, and not in your cordless phone. Call the telephone company and report the problem since the NID and anything beyond it falls under their responsibility.

Unplug your cordless phone including its base unit and plug it into the vacant jack inside the NID. Plug the power cord of the base unit into an electrical socket or extension cord, turn on the handset and listen for a dial tone. Place a call to test the base unit and the handset. If your phone is working fine at this point, then the problem lies in the wiring within your house and not in the cordless phone.

Unplug all other electronic devices connected to your telephone line such as fax machines, network routers, modems, security equipment and caller ID devices and listen for a dial tone each time you unplug a device to find out if any of the devices is causing the problem.

Except for your cordless phone, unplug each landline phone connected to the phone line one by one and listen for a dial tone each time you unplug a phone to find out if any of the corded phones is causing the problem.

Look for the copper prongs or contact pins at the bottom of the handset cradle on the base unit. The prongs or contact pins on the base unit engage the copper contact plates at the bottom of the handset to allow the handset batteries to recharge by feeding electricity to the handset each time you seat the handset . Clean the contact pins and the plates by scrubbing them gently using a pencil eraser.

Depress the contact pins at the bottom of the handset cradle several times using your index finger, and see if the pins pop out each time you lift your finger. The pins should easily slide up and down and should engage the contact plates at the bottom of the handset when the handset is seated to allow electricity to pass through. Dab the prongs very lightly with a cotton swab dipped in rubbing alcohol to loosen them in case they have become sticky.

Unplug each modular connector attached to the base unit from its jack. Peek inside each jack and look for any bent or misaligned contact pins inside. Straighten out and align any deformed, bent or misaligned pins using needle-nose pliers. Replug each connector back to its jack and place a call to see if the problem has been fixed.

Remove the power cord and inspect it for any sign of damage. Look for puncture marks, cuts, deformation or burnt plastic along the cable and on the plug. Smell the power adaptor or small plastic box attached somewhere along the cable for burnt odour which is indicative of burnt electrical wiring inside it. Replace the power cord and adaptor if you find any damage.

Look at the antenna on the base unit. Each cordless phone has a base unit antenna that catches the signals coming from the handset, and any damage to the antenna can severely affect the ability of the base unit to transmit radio signals. Check to see if it is missing or damaged. In case it is damaged, call the manufacturer to find out if a replacement is available and have the antenna replaced.

Look for the battery compartment on the handset. Unsnap or slide open the compartment and inspect the battery. Press the battery connector or plug at the end of two thin wires against the battery to make sure that it has not become loose or disconnected. Replace the cover and sit the handset onto its cradle, and verify that the charging indicator light comes on. Allow the phone to charge overnight and check the power indicator light to see if the handset will hold charge. Replace the battery if it does not hold a charge or if it becomes discharged after only a few hours of use.


Unless you are a qualified electronics technician, never attempt to repair the electronics inside a cordless phone base unit. Doing so without the proper experience and training can damage or add more damage to your phone and can put you at risk of receiving electrical shock.

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About the Author

Raul Avenir has been writing for various websites since 2009, authoring numerous articles concentrated on business and technology. He is a technically inclined businessman experienced in construction and real estate development. Aside from being an accountant, Avenir is also a business consultant. He graduated with a degree of Bachelor of Science in business administration.