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Knowledge document #97

Poor voice quality when conducting calls

When conducting calls, one of the following issues either occasionally occurs or always occurs:

  • When conducting calls, you experience disturbances such as echo, dropouts, delays or background noise.
  • A loud and annoying hiss is heard when conducting calls. 
  • The voice of one or both parties sounds distorted or "choppy".

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

1 Installing the latest software for your telephone

The following steps are only necessary if you are using a FRITZ!Fon:

  1. Install the latest software on the telephone.

2 Excluding repeater(s) as a cause of error

The following steps are only necessary if you use one or more repeaters to increase the DECT range of the FRITZ!Box and you hear the background noise when making calls with cordless telephones:

  1. Unplug all of the repeaters.
  2. Check whether you still hear background noise when you use a cordless telephone to make a call near the FRITZ!Box.
  3. If you no longer hear background noise, follow the steps in our guide Background noise when using a DECT repeater. In this case, the repeater is either not correctly connected with the FRITZ!Box or it was not positioned correctly.
    • If you can still hear background noise, plug the repeater in again and continue with the next section.

3 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.

4 Reducing the call volume on the telephone

  1. Reduce the call volume on the telephone.

    Note:If you want to reduce the call volume on your FRITZ!Fon, press the "down arrow" or "telephone book" icon on the control ring while speaking on the telephone.

5 Removing USB 3.0 devices from the FRITZ!Box

  1. For testing purposes, remove all of the USB 3.0 devices from the FRITZ!Box's USB ports.
  2. If the problem no longer occurs then, a USB device was interfering with the radio connection. Eliminate the interference caused by the USB device.

6 Registering cordless telephones with the FRITZ!Box

  1. Register all cordless telephones with the base station of the FRITZ!Box and switch off any other base stations.

7 Restoring the telephone to its factory settings and re-registering it

The following steps are only necessary if only a FRITZ!Fon is affected and other telephones do not have problems with voice quality:

Restoring the telephone to its factory settings

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

Deleting the telephone

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. Click the (Delete) button to delete the respective telephone.

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.

Re-registering the telephone

  1. Register the telephone with the FRITZ!Box.

The FRITZ!Box's echo compensation and traffic shaping functions guarantee high voice quality. However, if you still experience an echo, delays or short dropouts, they are caused by the telephone, your internet service provider or telephony provider, and cannot be influenced by the FRITZ!Box.

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