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Knowledge document #177

Conducting calls with the FRITZ!Box over another router

You can also use the FRITZ!box to conduct calls if another router (for example an IAD) in the network establishes the internet connection. With the FRITZ!Box you can

  • use any internet telephony provider from which you received login information for internet telephone numbers. The internet telephone numbers can either be from your provider or from a different internet telephony provider.
  • use the router's sockets for telephony devices, if your provider enabled them.
  • conduct calls over a landline (analog or ISDN).

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

1 Configuring internet telephone numbers

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

2 Entering a STUN server

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephone Numbers" in the "Telephony" menu.
  3. Click the (Edit) button for the respective internet telephone number.
  4. Check if the field "STUN server" is present under the fields for entering your login information.
  5. If the field is present and empty, enter the address of your internet telephony provider's STUN server and click "OK".
    • If the field is not present:
      1. Select "Other provider" from the drop-down list, even if you are using a preconfigured internet telephony provider.
      2. Check if the "STUN server" field is present now.
      3. If the field is present, enter the address of your internet telephony provider's STUN server and click "OK".
        • If the field is not present, click "Cancel". The STUN server is already preconfigured.

3 Setting up port forwarding for internet telephony

Since the upstream router establishes the internet connection, you must set up port forwarding for telephony:

Setting up automatic port forwarding

If you enable port forwarding in the FRITZ!Box, the FRITZ!Box sends IP packets at regular intervals and the router's port forwarding automatically remains enabled:

  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 "Changing the Settings" in the "Telephony connection" section.
  5. Enable the option "Keep port sharing of the internet router enabled for telephony".
  6. Select a suitable time interval. Select "30 sec." if you do not know how long temporary port forwarding rules will be maintained.
  7. Click "Apply" to save the settings.

Setting up static port forwarding

The following steps are only necessary if the router does not support automatic port forwarding by the FRITZ!Box:

Note:Refer to the manufacturer of the router for information on setting it up; for example, consult the manual.

  1. On the router, configure port forwarding from UDP port 5060 to port 5060 on the FRITZ!Box.
  2. If your telephony provider supports encrypted telephone calls via TLS, for example Telekom, Easybell, dus.net, also configure port forwarding from TCP port 5061 to port 5061 on the FRITZ!Box.

4 Setting up the FRITZ!Box for landline telephony

If the router has a socket for connecting telephony devices that has been activated by your provider, connect the FRITZ!Box to the router as follows:

Note:You can also connect the FRITZ!Box to a landline, if one is available. Refer to the FRITZ!Box's manual for information on connecting it.

Connecting the FRITZ!Box

If both ISDN and analog end devices can be connected to the router, connect the FRITZ!Box to the to the router's ISDN port:

Note:You can also make a suitable cable yourself. You can find information on cable assignment in the guide Assignment of cables, adapters, and sockets.

  1. Plug the longer end of the DSL/telephone cable ("Y cable") included with delivery into the socket labeled "DSL" on the back of the FRITZ!Box.
  2. If the router has a socket for ISDN devices, plug the black plug on the split end of the cable directly into this socket.
    • If the router only has a socket for analog devices, plug the black plug on the split end of the cable into the TAE/RJ45 adapter included with delivery first and then plug it into this socket.

Configuring landline numbers

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

Now you can assign your telephone numbers to the telephony devices connected to the FRITZ!Box and use them for making and receiving calls.

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