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Knowledge document #42

Registering an IP telephone with the FRITZ!Box and setting it up

You can register a total of ten IP telephones (including FRITZ!App Fon) with the FRITZ!Box. IP telephones are available as telephony devices (hardphones), as a combination of an adapter and a regular telephone, or as a software solution for your computer.

If the FRITZ!Box is connected to a landline, you can use the telephone to conduct calls over the internet and from your landline after setting it up. In addition, you can register your telephone with the FRITZ!Box over the internet or a VPN connection and then make calls over the FRITZ!Box from home or on the go.

Note:You can also configure the IP telephones so that they only use the FRITZ!Box's internet connection and establish the connection to the internet telephony provider themselves. You can then only make calls over the internet with the telephones but not internal calls.

Requirements / Restrictions

  • The IP telephone must use an IP address from the FRITZ!Box's IP address range.
  • Various FRITZ!Box functions are not available for IP telephones. This is the case with busy on busy, call-back on busy / no response, individual do not disturb settings, accessing telephone books, controlling certain FRITZ!Box functions such as enabling or disabling Wi-Fi, loading factory settings, and setting up call diversions, for example.
  • IP telephones cannot be used for fax and data connections.

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

1 Configuring telephone numbers in the FRITZ!Box

Configure all of the available telephone numbers in the FRITZ!Box:

Configuring internet telephone numbers

  1. Configure the internet telephone numbers in the FRITZ!Box.

Configuring landline numbers

  1. Configure the landline number in the FRITZ!Box.

Configuring a mobile telephone number

  1. Configure the mobile telephone number in the FRITZ!Box.

2 Connecting the telephone to the FRITZ!Box

  1. Either use Wi-Fi or a network cable to connect the telephone to the home network of the FRITZ!Box (not the guest network).

3 Configuring a telephone in the FRITZ!Box

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. Click the "Configure New Device" button.
  4. Enable the option "Telephone (with or without answering machine)" and click "Next".
  5. Enable the option "LAN/Wi-Fi (IP telephone)" and click "Next".
  6. Enter a username that is at least eight characters long.
  7. Enter a password that is at least eight characters long and differs significantly from the username. Then, click "Next".
  8. Select the number the telephone should use for making calls and click "Next".
  9. Select the telephone numbers that the telephone should react to and click "Next".
  10. 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.

4 Entering login information on the telephone

  1. On the telephone, configure an internet telephone number with the login information for the FRITZ!Box.
  2. Enter the username displayed in the FRITZ!Box user interface as the username for the telephone number.
  3. Enter the same password that you entered in the FRITZ!Box user interface.
  4. Enter fritz.box or the IP address of the FRITZ!Box (192.168.178.1 in the factory settings) as the SIP registrar. If you want to register the telephone with the FRITZ!Box over the internet, enter the public IP address of the FRITZ!Box as the SIP registrar instead.

    Note:Most internet service providers clear the internet connection on a daily basis ("automatic disconnection") and assign the FRITZ!Box a different IP address when the connection is automatically re-established. The FRITZ!Box can be accessed over the internet under its MyFRITZ! address at all times, even if its public IP address changes at regular intervals.

  5. Do not enter a STUN server.

Now you can use the telephone to make and receive calls using the telephone numbers you configured.

5 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.

6 Configuring the telephone for registration from the internet

If you want to use the telephone in your home network as well as over the internet, you must allow registration from the internet:

ATTENTION!For security reasons, we recommend that you do not register IP telephones over the internet; instead, only register them over an encrypted VPN connection, for example over a VPN connection between two FRITZ!Boxes.

  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 "Account Information" tab.
  5. Enable the option "Allow registration from the internet".
  6. 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.

7 Supported telephony functions

Normally you can use a number of FRITZ!Box functions using a telephone keypad. However, this only works to a limited extent with IP telephones. The functions CLIP (displaying caller's telephone number) and CLIR (blocking your telephone number from being displayed) can also be used when conducting calls with IP telephones. You can also conduct internal telephone calls with other telephones, pick up calls from other telephones connected to the FRITZ!Box, and use quick-dial numbers and vanity codes from the FRITZ!Box telephone book.

Note:You can find the internal numbers of the telephony devices under "Telephone Book > Internal Numbers" in the FRITZ!Box user interface.