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Cannot make outgoing calls

You can't make outgoing calls? The telephone does not work or the telephone number is not registered? ✔ Here's what to do.

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 Installing the latest FRITZ!OS

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

2 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 and on the FRITZ!Box, confirm that the procedure may be executed, if you are asked to do so.

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 Enabling calls to international and premium numbers

After setting up telephony, you can only make national calls and calls to emergency numbers. You can disable this security feature:

  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. Click on "Change selection" in the section "Security".
  5. Uncheck the boxes for all of the IP telephones that are allowed to dial international and premium numbers.
  6. Click "OK" to save the settings and on the FRITZ!Box, confirm that the procedure may be executed, if you are asked to do so.

5 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.

6 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.

7 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.

8 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:

9 Defining telephone numbers for FRITZ!App Fon

  1. Start FRITZ!App Fon.
  2. Tap the the three-dot menu on the top right (Android) or "More" (iOS) and then tap "Settings".
  3. If you are using FRITZ!App Fon in iOS, tap "Telephone Numbers".
  4. If you are using FRITZ!App Fon in Android and use the app with several FRITZ!Boxes, first tap on the desired FRITZ!Box.
  5. Under "Outgoing calls", select the number to be used by FRITZ!App Fon for making calls.
  6. Under "Incoming Calls", specify which telephone numbers FRITZ!App Fon should react to when you receive calls.

10 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.

    Important:Do not use the wizard configure FRITZ!App Fon. FRITZ!App Fon is automatically set up again if you delete the app from your smartphone and reinstall it.

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.