How do I set up a VPN connection between a D-Series phone and a Fritz!Box to operate the phone as an external extension?



  •     FRITZ!Box firmware version 06.30 or higher
  •     Telephone firmware version 1.2 or higher
  •     Fixed IP or a DynDns account via which the FritzBox can be reached externally
  •     IPv4 address (IPv6 VPN connections are not supported by the FRITZ!Box)



Add a new user for the phone's VPN connection in the FritzBox under System / Fritz!Box User, e.g. D400Home and set a secure password; you do not need to enter an e-mail address.

Give this user the VPN authorisation, all other authorisations are not required for the VPN connection; the option Access also allowed from the Internet does not need to be active either.

Accept the settings and then display the VPN settings.

Make a note of the user name, the password you have assigned, the server address (fixed external IP or Dyn address) and the IPSec key.


In the web interface of the device, the connection must be activated via the VPN switch on the VPN tab and IPsec Xauth PSK must be set as the VPN type.

Now enter the following data:


  • Name: Any name for the VPN connection, e.g. VPN company
  • Server: Server address (fixed external IP or Dyn address) of the Fritz!Box
  • User name: User name for the VPN connection, in our example D400Home
  • Password: Password of the user D400Home from the Fritz!
  • DNS server: remains empty
  • Search domains: remains empty
  • Forwarding routes: IP addresses that can be reached via this VPN connection can be left blank., for example, stands for the address range -
  • IPsec ID: User name for the VPN connection, in our example D400Home
  • Pre-installed IPsec key:IPSec key from the Fritz!Box
  • The following certificates, keys or OpenVPN configurations do not need to be used in our example.

When you save the settings, the VPN connection is established. Successful connection establishment is signalled with a key symbol in the top line of the D-400 display.

A key can be assigned to the VPN function to conveniently switch the VPN connection on or off as required; the connection can also be controlled via the phone menu under Settings / Network / VPN.