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Knowledge document #28

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 use FRITZ!App Fon to make calls over the internet. The telephone number may not be registered and one of the following error messages or a different message referring to the telephone number may be displayed in the event log of the FRITZ!Box:

  • "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."

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 "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.

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 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.

4 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, a solution on the part of the FRITZ!Box is not possible.

5 Defining telephone numbers for FRITZ!App Fon

  1. Start FRITZ!App Fon.
  2. Tap the gear symbol (Android) or the three-dot menu (iOS) on the top right 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 the gear icon next to 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.

6 Reconfiguring your telephone

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. Delete FRITZ!App Fon from the list of telephony devices. To do so, click the corresponding (Delete) button.
  4. Click "FRITZ!Box Users" and then the tab "Apps" in the "System" menu.
  5. Delete FRITZ!App Fon from the list of apps. To do so, click the corresponding (Delete) button.
  6. Uninstall or delete FRITZ!App Fon from your smartphone.
  7. Download the app from the Google Play Store or the Apple App Store and reinstall the app on your smartphone.

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.

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