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Knowledge Base document #65

Cannot register a cordless phone

Registration of a cordless phone fails. The following messages are displayed:

  • In the FRITZ!Box user interface: 'Registration with the DECT base station failed. The reason for the error is displayed on the cordless (DECT) phone.'
  • On the phone's display: 'Registration at Base 1, 2, 3 or 4 failed' or 'Search for base'

Simply proceed as described below. After each measure, check whether the problem is solved.

Note:All instructions on configuration and settings given in this guide refer to the latest FRITZ!OS for the FRITZ!Box.

1 Maximum number has been reached

You can register up to six cordless phones, DECT headsets, or DECT door intercom systems with the FRITZ!Box. If six phones or four phones, a headset, and one door intercom system have already been registered, you cannot register any more phones.

Note:You can delete phones that you are no longer using under 'Telephony > Telephony Devices' in the FRITZ!Box user interface.

2 Restarting the FRITZ!Box

  1. Click on 'System' in the FRITZ!Box user interface.
  2. Click on 'Backup' in the 'System' menu.
  3. Click on the 'Restart' tab.
  4. Click on the 'Restart' button.

3 Unlocking the buttons

  1. Click on 'System' in the FRITZ!Box user interface.
  2. Click on 'Buttons and LEDs' in the 'System' menu.
  3. Click on the 'Keylock' tab.
  4. Disable the 'Buttons locked' checkbox.

4 Checking whether the phone supports DECT-GAP

The phone must support the DECT-GAP profile. DECT-GAP is a common standard for cordless phones and wireless data transmission that is supported by all FRITZ!Fon models, for example:

  1. Check the phone's manual or ask the manufacturer whether the phone supports the DECT-GAP profile. If it does not support DECT-GAP, we do not guarantee that it will function with the FRITZ!Box.

5 Disabling 'DECT Eco'

  1. Click on 'Telephony' in the FRITZ!Box user interface.
  2. Click on 'DECT' in the 'Telephony' menu.
  3. Disable the option 'DECT Eco' in the section 'Radio Field Strength'.
  4. Click on 'Apply' to save the settings.

Do not re-enable the 'DECT Eco' option until you have successfully registered the phone with the FRITZ!Box.

6 Setting a PIN

You may be using an incorrect PIN to register the phone with the FRITZ!Box. Therefore, set a new PIN for the FRITZ!Box's base station:

  1. Click on 'Telephony' in the FRITZ!Box user interface.
  2. Click on 'DECT' in the 'Telephony' menu.
  3. Enter a four-digit PIN in the section 'Registration'.
  4. Click on 'Apply' to save the settings.

7 Installing the latest FRITZ!OS for the FRITZ!Box

  1. Install the latest FRITZ!OS on the FRITZ!Box.

8 Restoring the phone to its factory settings

The following steps are only necessary if the problem occurs when using a FRITZ!Fon:

  1. Press the 'Menu' key on the phone.
  2. Scroll to 'Settings' and press 'OK'.
  3. 'Reset' > 'OK' > 'OK'

9 Disabling expanded security functions

The following steps are only necessary if the problem occurs with a cordless phone from a different manufacturer:

  1. Click on 'Telephony' in the FRITZ!Box user interface.
  2. Click on 'DECT' in the 'Telephony' menu.
  3. Disable the expanded security functions in the section 'Security'.
  4. Click on 'Apply' to save the settings.

10 Resetting FRITZ!Box and using the wizard to register the phone

Settings in the FRITZ!Box may be preventing the phone from being registered. Therefore, restore the FRITZ!Box to factory settings and then use the wizard in the FRITZ!Box user interface to register the phone:

Saving settings of the FRITZ!Box

  1. Save the FRITZ!Box settings.

Saving the FRITZ!Box phone books

  1. Click on 'Telephony' in the FRITZ!Box user interface.
  2. Click on 'Phone Book' in the 'Telephony' menu.
  3. Select a phone book, click on the 'Save' button, and save the phone book as an XML file on your computer.

    Important:If the browser blocks the file download, click on 'Keep' in Microsoft Edge and Chrome.

  4. Save all of the phone books stored in the FRITZ!Box, one after the other.

Loading the FRITZ!Box factory settings

  1. Load the FRITZ!Box's factory settings.

Using the FRITZ!Box wizard to register a phone

  1. Click on 'Telephony' in the FRITZ!Box user interface.
  2. Click on 'Telephony Devices' in the 'Telephony' menu.
  3. Click the 'Configure New Device' button.
  4. Enable the option 'Phone (with or without answering machine)' and click on 'Next'.
  5. Enable the option 'Cordless (DECT) phone' and click on 'Next'.
  6. Start the registration procedure on the phone, then click on 'Connect' and follow the instructions.
  7. If you are asked for the PIN of the base station, enter 0000 on your phone. This is the factory setting of the FRITZ!Box.
  8. If you could successfully register the phone with the FRITZ!Box, import the phone books that you saved and reconfigure the FRITZ!Box.

    Important:Do not restore the settings saved in the file 'fritzbox[...].export', otherwise the registration of new cordless phones may fail again.

11 Testing a different phone

Test whether you can register a different cordless phone with the FRITZ!Box. Use a phone that supports the DECT-GAP standard:

  1. Restore the FRITZ!Box settings.
  2. Use the wizard to register the other cordless phone with the FRITZ!Box.
  3. If you can register the other cordless phone with the FRITZ!Box, the first phone is incorrectly configured or defective.
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