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Cannot make outgoing calls over the internet

You cannot make calls over the internet with a telephone or telephones connected to the FRITZ!Box, or it may not be possible to call only certain numbers. The problem either occurs sporadically or all the time. When it occurs, the telephone number may not be registered at that time and one of the following error messages or a different message referring to the telephone number may be displayed on the "Overview" page or in the event log of the FRITZ!Box:

  • "[number] telephone numbers active, none of these registered"
  • "Registration of internet telephone number [number] failed. Reason for error: DNS error"
  • "Registration of internet telephone number [number] failed. Reason for error: Remote site not responding. Timeout."
  • "Registration of internet telephone number [number] failed. Remote site reports reason for error: [40x, 50x, 500, 503]"
  • "Internet telephony registration failed [number] Reason for error: [401, 402, 403]"
  • "Internet telephony with [Number] failed. Reason for error: [404, 405, 406, 407, 408, 50x]"
  • "Internet telephony with [number] via [registrar] failed. Reason for error: Not Acceptable Here (488)"
  • "Internet telephony with [number] via [registrar] failed. Reason for error: Timeout: The call was not accepted. [Message]"
  • "Internet (telephony) connection cleared."

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

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

1 Entering your location information

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephone Numbers" in the "Telephony" menu.
  3. Click on the "Line Settings" tab.
  4. Select your country from the drop-down list under "Location Information". If your country is not listed, select "Other country".
  5. For the "Country code", enter the leading zeros in the first field and the country code in the second field (for example, enter "00" and "49" for Germany, see fig.).
  6. For the "Area code", enter the leading zero in the first field and the area code in the second field (for example enter "0" and "30" for Berlin, see fig.).

    Fig.: Entering the country code and area code (e.g. for Germany and Berlin)

  7. Click "Apply" to save the settings.

2 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.

3 Deleting carrier prefixes (provider prefixes)

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Call Handling" in the "Telephony" menu.
  3. Click on the "Provider Prefixes" ("Carrier Prefixes") tab.
  4. Delete all entries under "Global Provider Prefix" ("Global Carrier Prefix") and "Additional Provider Prefixes" ("Additional Carrier Prefixes").
  5. Click "Apply" to save the settings.

4 Reconfiguring telephone numbers

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephone Numbers" in the "Telephony" menu.
  3. Click the (Delete) button for the telephone number.
  4. Reconfigure the telephone number and select your internet telephony provider during setup.
  5. If you are unable to register the telephone number after setup, contact your provider to have them check your telephone number and login information.

5 The provider rejects the call attempt

This section only applies if the message "Internet telephony [...] failed. Reason for error: Not Acceptable Here (488)" is displayed under "System > Event Log" in the FRITZ!Box user interface when the error occurs. This message from your provider means that they do not make a requested function available for your line. This could be caused by the following reasons, for example:

  • The provider does not support the requested codec.
  • The provider does not support calls to the destination telephone number, for example calls to premium numbers.
  • The provider does not allow you to make more than one call at a time.

Therefore, the FRITZ!Box cannot solve this problem.

6 Setting up the FRITZ!Box to conduct calls over another router

The following steps are only necessary if the FRITZ!Box does not establish its own connection to the internet, and uses the internet connection of another router in the network instead:

7 Setting your analog telephone to tone dialing

  1. Set your device to "tone dialing" (DTMF) and not "pulse dialing". Pulse dialing is no longer state of the art and can lead to dialing problems on a telephone system. We therefore cannot guarantee the flawless operation of connected devices on the FRITZ!Box with pulse dialing. If tone dialing is selected, you hear a tone when you press a number key; with pulse dialing, you hear clicking sounds. Refer to the manufacturer of the device for information on how to set it up, for example consult the manual.

8 Reconfiguring your telephone

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. Delete the telephone that you cannot make calls with. To do so, click the corresponding (Delete) button.
  4. Use the wizard to reconfigure the telephone: To do so, click the "Configure New Device" button and follow the instructions.

9 Disabling HD telephony

The following steps are only necessary if the problem occurs with a cordless telephone:

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. Click the (Edit) button for the respective telephone.
  4. Click on the "Telephony Device Features" tab.
  5. Select the option "HD disabled" from the drop-down list in the section "HD Telephony". If the section is not displayed, enable the Advanced View first.
  6. Click "OK" to save the settings.

The FRITZ!Box is now fully configured for making calls over the internet. If you still have problems, your internet telephony provider may be experiencing technical difficulties.