ATT CL4940 Troubleshooting

Corded answering system with back lit display, identified by model number CL4940.

The telephone does not respond or show any signs of powering on.

Make sure the power cord is securely plugged into the wall outlet and into the back of the telephone. If this does not work, reset the telephone. To do this, unplug the electrical power. Wait for approximately 15 seconds, then plug it back in. Allow up to one minute for the telephone to rest.

The display shows no line. I cannot get a dial tone.

Make sure you plug the telephone line cord securely and firmly into the telephone and the telephone wall jack

If the previous suggestions do not work, disconnect the telephone line cord from your telephone and connect the telephone line cord to another telephone. If there is no dial tone on that other telephone either, your telephone line cord may be defective. Install a new telephone line cord.

If changing the telephone line cord does not help, the wall jack (or the wiring to this wall jack) may be defective. Try using a different wall jack in your home to connect your CL4940 telephone, or contact your telephone service provider.

The system may have operation troubles. To solve this, reset the phone by disconnecting the electrical power for about 15 seconds. Then plug it back in and wait for one minute to allow the telephone to reset.

  • Try all the suggestions, as mentioned above.
  • Make sure you have a dial tone before dialing.
  • Eliminate any background noise. Noise from a television, radio, or other appliance may cause the phone to not dial out properly. If you cannot eliminate the background noise, first try moving the telephone before dialing, or dialing from another room with less background noise.
  • If other phones in your home are having the same problem, contact your telephone service provider.
  • Disconnect the telephone from the telephone jack, and plug in a different telephone. If you still hear other calls, call your telephone service provider.
  • You need to set the system clock.

1. Press MENU -> press ▽/△ to scroll to Set date/time -> press SELECT.

2. Use the dialing keys (0-9) to enter the month (MM), date (DD) and year (YY) -> Press


3. Use the dialing keys (0-9) to enter the hour (HH) and minute (MM).

4. Press ▽/△ to select AM or PM -> press SELECT to save your setting.

You can press CANCEL to go back to the previous field and make correction.

  • If you subscribe to high-speed internet service (DSL - digital subscriber line) through your telephone line, you must install a DSL filter between the telephone line cord and the telephone wall jack. The filter prevents noise and caller ID problems as a result of DSL interference. Contact your DSL service provider for more information about DSL filters.
  • Do not install this phone near a microwave oven or on the same electrical outlet. You may experience decreased performance while the microwave oven is operating.
  • If you plug your phone in with a modem or a surge protector, plug the phone (or modem/surge protector) into a different location. If this does not solve the problem, relocate your phone or modem farther apart from one another, or use a different surge protector.
  • If other phones in your home are having the same problem, contact your telephone service provider.


My phone does nor ring on incoming calls. Please help to solve the problem

Hugo Davila - Reply

I have 4 att CL4940 phones. No one rings when receiving incoming calles.

Hugo Davila - Reply

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