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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.

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

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

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

2 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.

3 Excluding DECT 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.

4 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.

5 Finding the ideal location for the FRITZ!Box

You can use the alignment aid to find the ideal location for the FRITZ!Box and the best position for the mobile network antennas:

  1. Click "Internet" in the FRITZ!Box user interface.
  2. Click "5G Information" in the "Internet" menu.
  3. Click on the "Reception" tab.
  4. Click the "Start Alignment Aid" button.
    • Now the current signal strength of the antennas is displayed by the LEDs on the FRITZ!Box (in five levels) and in the user interface.
  5. Select a location for the FRITZ!Box where the signal strength is as high as possible. When doing so, note the following:
    1. Position the antennas of the FRITZ!Box so that they are as perpendicular as possible (90° angle). For example, position one antenna vertically and the other horizontally.
    2. Place the FRITZ!Box as close to an outside wall as possible. If you know where your provider's mobile radio cell is located, place the FRITZ!Box by the wall facing the mobile radio cell.

      Important:If you place the FRITZ!Box in the attic or on a window sill, make sure that the permissible operating temperature of 0° to 40° Celsius is not exceeded.

    3. Select a location for the FRITZ!Box that is free from obstacles, sources of interference, and heat that is about one meter above the ground.
    4. Do not set up the FRITZ!Box in the corner of a room.

6 Checking the quality of your LTE connection

A bad LTE connection has the greatest impact on applications that require real-time transmission, such as internet telephony. It especially affects upload, thus affecting the quality of voice data being transmitted to the party being called. Therefore, check whether the quality of the LTE connection is sufficient for conducting internet calls:

  1. Click "Internet" in the FRITZ!Box user interface.
  2. Click "5G Information" in the "Internet" menu.
  3. Click on the "Mobile" tab.
  4. Check which "SINR" and "RSRP" values are shown for the the FRITZ!Box's "Antenna 1" in the "Antenna Signal and Connection Quality" section.
  5. If the SINR values are positive and the RSRP values are better than -105, continue with the next section. The signal quality of the LTE connection is sufficient for conducting internet calls.

    Example:
    If the SINR value is 10 and the RSRP value is -95, the poor voice quality you are experiencing is normally not due to the LTE connection.

    • If the SINR values are negative and the RSRP values are lower than -105, you may experience disturbances when conducting calls over the internet due to the bad LTE signal quality.

      Example:
      If the SINR value is -3 and the RSRP value is -115, the poor voice quality you are experiencing is normally due to the LTE connection.

      If you are using your FRITZ!Box in the outdoor coverage area of your LTE provider or in buildings with a strong shielding effect due to structural conditions or the surrounding environment, connect an outdoor LTE antenna to the FRITZ!Box. When used at that location, the signal strength of the FRITZ!Box's LTE antennas is not sufficient to achieve an optimum LTE connection.

7 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.

8 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.

9 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.

10 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.

11 Configuring the FRITZ!Box for internet telephony

Setting up a prioritization rule for internet telephony

  1. Click "Internet" in the FRITZ!Box user interface.
  2. Click "Filter" in the "Internet" menu.
  3. Click on the "Prioritization" tab.
  4. Check if there is a rule for "Internet telephony" under "Real-Time Applications".
  5. If there is no rule, click "New Rule".
  6. Select "All devices" (default) as the network device from the drop-down list.
  7. Select "Internet telephony" from the drop-down list "Enter the network application:".
  8. Click "Apply" to save the settings.

Configuring other applications

Applications such as file sharing software and online games establish many simultaneous internet connections. Although the "Traffic Shaping" function of the FRITZ!Box ensures that voice data is prioritized and evenly transmitted, for technical reasons it can only compensate for disturbances caused by these applications to a limited extent. This is why many applications offer the following setting options:

  1. Decrease the number of simultaneous connections allowed by the application.
  2. Reduce the maximum throughput available in the application..
  3. If you still experience problems or the application does not offer these settings options, configure the application as a background application in 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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