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Setting up FRITZ!App Fon

FRITZ!App Fon allows you to conveniently make telephone calls over the FRITZ!Box with your smartphone when you are at home – the smartphone functions as an IP telephone. You can also use FRITZ!App Fon with several FRITZ!Boxes and thus make calls over different FRITZ!Boxes. For this you must set up FRITZ!App Fon once on each FRITZ!Box as described here. After setting it up, you can use FRITZ!App Fon in the entire home network and conduct calls over a VPN connection, allowing you to then make calls over the FRITZ!Box from home or on the go.

Requirements / Restrictions

  • iOS 14.0 or later or Android 9.0 or later is installed on the smartphone or tablet.

    Note:An old version of FRITZ!!App Fon can be installed with older versions of Android. However, we no longer update or support this version.

  • FRITZ!App Fon cannot be registered or used over the Wi-Fi guest access.
  • A maximum of ten IP telephones (including FRITZ!App Fon) can be registered.
  • In iOS, incoming calls cannot be signaled over a VPN connection.
  • Various FRITZ!Box functions cannot be used with FRITZ!App Fon. These include call transfer, busy on busy, call-back on busy / no response, do not disturb function for individual numbers, the ability to control certain FRITZ!Box functions such as enabling or disabling Wi-Fi, loading factory settings, and setting up call diversions.

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

1 Preparations

Setting up a Wi-Fi connection to the FRITZ!Box

When setting up the app, the smartphone or tablet must be connected with the FRITZ!Box's Wi-Fi network (not the guest network):

Configuring the FRITZ!Box to allow access for applications

In the factory settings, the FRITZ!Box is configured to allow applications to access it. If you changed the FRITZ!Box's settings, grant applications access to the FRITZ!Box again:

  1. Click "Home Network" in the FRITZ!Box user interface.
  2. Click "Network" in the "Home Network" menu.
  3. Click on the "Network Settings" tab.
  4. If available, click "Additional Settings" in the section "WAN setting" or "LAN Settings" to display all of the settings.
  5. Enable the option "Allow access for applications" in the section "Access Settings in the Home Network".
  6. Click "Apply" to save the settings.

Disabling the VPN connection

When setting up the app, no VPN connection (for example NordVPN) and no comparable internet anonymization services (for example Apple iCloud Private Relay) may be active on the smartphone or tablet:

  1. Disable all of the VPN connections on the mobile device.

2 Installing FRITZ!App Fon

  1. Install FRITZ!App Fon from the Google Play Store or the Apple App Store on your smartphone.
  2. Start FRITZ!App Fon.
  3. Enter the FRITZ!Box password. If you are asked to enter a username and password, enter the account information of a FRITZ!Box user who is authorized to use FRITZ!App Fon.

    Note:You can edit the account information and access rights of users under "System > FRITZ!Box Users" in the user interface.

  4. On the FRITZ!Box, confirm that the procedure may be executed, if you are asked to do so.

FRITZ!App Fon is now automatically configured as an IP telephone on the "LAN/Wi-Fi" port in the FRITZ!Box.

3 Assigning telephone numbers

Do not configure the telephone numbers for FRITZ!App Fon in the FRITZ!Box user interface, configure them in the app itself:

  1. Start FRITZ!App Fon.
  2. Tap the three-dot menu 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.

4 Enabling calls to international and premium numbers

IP telephones (for example FRITZ!App Fon) and telephones connected to a Mesh Repeater can only be used to 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 Configuring FRITZ!App Fon for VPN

If you set up a VPN connection in Android or iOS, you can use FRITZ!App Fon in Android over the VPN connection without configuring any other settings. The following settings are necessary in iOS so that outgoing calls can be made:

  1. Start FRITZ!App Fon.
  2. Tap "More" and then "Settings".
  3. Tap "Select FRITZ!Box".
  4. Tap "Enter the IP address manually".
  5. Instead of entering, enter the local IP address of the FRITZ!Box ( in the factory settings).

6 Selecting a telephone book

With FRITZ!App Fon you can access the local contacts on your telephone and all of the FRITZ!Box telephone books, regardless of whether the telephone books are saved in the FRITZ!Box or you are using the telephone book of an online provider:

Allowing access to contacts in iOS

In order for FRITZ!App Fon to access the local contacts on your iOS device in iOS, you must enable access to your contacts for FRITZ!App Fon:

  1. Open the iOS settings.
  2. Tap "Privacy" and then "Contacts".
  3. Allow FRITZ!App Fon access to the contacts.

Switching telephone books

  1. Start FRITZ!App Fon.
  2. Tap "Phone book".
  3. Tap the three-dot menu in Android and then "Adjust Telephone Book Display" or tap the telephone book symbol (on the top right) in iOS.
  4. Select the telephone book you want to use with FRITZ!App Fon. Smartphone contacts or "iPhone contacts" are the local contacts on your telephone. The names displayed for the FRITZ!Box telephone books are the names you gave them in the FRITZ!Box user interface.

When you start FRITZ!App Fon now, the app automatically connects to the FRITZ!Box and remains active in the background. This way you can make calls quickly and directly over the FRITZ!Box. If you also use other telephony apps (such as Joyn) on your smartphone, you must always start FRITZ!App Fon before you start the other telephony apps because otherwise automatic registration with the FRITZ!Box may fail.