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Knowledge document #3253

Cannot register an IP telephone or app

Registration of an IP telephone or a telephony app (for example FRITZ!App Fon) with the FRITZ!Box fails. The internet telephone number configured in the IP telephone or the app does not get registered. There is a timeout on the telephone. The error either occurs right after setup or during operation.

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 Guest access may not be used for connecting the IP telephone

You cannot register an IP telephone via the LAN and Wi-Fi guest access. Therefore, make sure that the IP telephone is not connected with the FRITZ!Box via the guest access:

  1. Either use Wi-Fi or a network cable to connect the telephone to the home network of the FRITZ!Box.

2 Updating the telephony app

  1. Update all of the telephony apps on your smartphone. Check the Google Play Store or Apple App Store for updates.
  2. When you have finished updating, switch the smartphone off and then on again.

3 Changing login information for the respective IP telephone

Changing the login information in the FRITZ!Box

  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 IP telephone configured for the "LAN/Wi-Fi" port.
  4. Click on the "Account Information" tab.
  5. Enter a username that is at least eight characters long.
  6. Enter a password that is at least eight characters long and differs significantly from the username.
  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.

Changing the login information in the IP telephone

  1. Enter the new login information in the IP telephone for the respective internet telephone number.

4 Deleting the telephony app an reinstalling it

  1. Uninstall or delete the respective telephony app from your smartphone.
  2. Download the app from the Google Play Store or the Apple App Store again and reinstall the app on your smartphone.

5 Reconfiguring the IP telephone for the "LAN/Wi-Fi" port

Deleting the telephone

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. Delete the respective IP telephone configured for the "LAN/Wi-Fi" port. To do so, click the corresponding (Delete) button.

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.

Reconfiguring your telephone

  1. Reconfigure the telephone in the FRITZ!Box.

    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.

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