FRITZ!Box 7390 – Service - Knowledge Base

FRITZ!Box 7390 – Service
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Loud background noise when using FRITZ!DECT Repeater

As soon as a FRITZ!DECT Repeater is registered with the FRITZ!Box, you can hear loud background noise when conducting calls with a cordless telephone.


  • The repeater is not properly connected with the FRITZ!Box or it was not positioned correctly.

Note:The configuration procedure and notes on functions given in this guide refer to the latest FRITZ!OS for your FRITZ!Box.

1 Preparations

DECT is a continuously evolving technology. To ensure that your FRITZ!Box is up-to-date, first install the latest FRITZ!OS:

2 Configuring the FRITZ!Box

Enabling encryption

  1. Click "DECT" in the FRITZ!Box user interface.
  2. Click "Base Station" in the "DECT" menu.
  3. Enable the option "Permit only secure DECT connections (recommended)" in the "Security" section.
  4. Click "Apply" to save the settings.
  5. If the option was disabled, you must then restart the FRITZ!Box once using the user interface ("System > Backup > Restart").

Setting a PIN

  1. Click "DECT" in the FRITZ!Box user interface.
  2. Click "Base Station" in the "DECT" menu.
  3. Enter "0000" as the PIN in the "Registration" section.
  4. Click "Apply" to save the settings.

Important:You cannot change the PIN once you have successfully registered the repeater!

3 Re-registering a repeater

Deregistering a repeater

  • Push the "DECT" button on the repeater and hold it down for at least 6 seconds, then immediately repeat this procedure once.

The "DECT" LED begins to flash as soon as the repeater is de-registered.

Restarting the FRITZ!Box

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

Establishing a DECT connection

  1. Plug the repeater into an outlet near the FRITZ!Box and push the "DECT" button on the repeater for 6 seconds.
  2. Now push the "DECT" button on the FRITZ!Box within 2 minutes. Hold down the button for at least 6 seconds until the "DECT" or "Info" LED on the FRITZ!Box begins to flash.

Now the repeater automatically registers itself with the FRITZ!Box. The "DECT" LED on the repeater remains lit as soon as the DECT connection has been established.

Important:After the connection is established, the FRITZ!Box checks whether new firmware is available for the repeater. If a new version of the firmware is found, it is updated immediately. The update procedure is completed as soon as the LEDs on the repeater stop flashing. This process may take several minutes.

4 Finding the ideal location for the repeater

  • Select a location for the repeater where a telephone that is connected directly with the FRITZ!Box still has flawless reception. The "DECT" LED on the repeater must remain lit. If the LED flashes, then the repeater is not connected to the FRITZ!Box. In addition, at the location you select for the repeater, voice transmission in both directions must be absolutely interference-free, even when using each of your telephones once the repeater has been turned off. Otherwise, the location is not a suitable place to position the repeater.