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Setting up an external fax in the FRITZ!Box

You can use a fax machine connected to an analogue extension or the socket for ISDN devices on your FRITZ!Box to send and receive faxes over the internet.

1 Enabling fax transmission with T.38

If you use an internet phone number for faxing, you must enable T.38 (fax over IP) in the FRITZ!Box for fax transmission. With T.38, a special network protocol is used for fax transmission instead of signal tones. This makes transmission significantly less susceptible to interference:

  1. Click on 'Telephony' in the FRITZ!Box user interface.
  2. Click on 'Phone Numbers' in the 'Telephony' menu.
  3. Click on the 'Line Settings' tab. If the tab is not displayed, your cable provider automatically configures the line settings during configuration. You cannot change these settings later. Your cable provider can provide you with information on the settings.
  4. Click on 'Changing the Settings' in the 'Telephony connection' section.
  5. Enable the option 'Fax transmission using T.38'.
  6. Click on 'Apply' to save the settings.

2 Reconfiguring the fax machine

Set up the fax machine in the FRITZ!Box, even if it is connected to the FRITZ!Box via an ISDN phone system:

  1. Click on 'Telephony' in the FRITZ!Box user interface.
  2. Click on 'Telephony Devices' in the 'Telephony' menu.
  3. If the fax machine is already displayed in the list of telephony devices, click on the (Delete) button for the fax machine.
  4. Reconfigure the fax machine: Click on the 'Configure New Device' button and follow the instructions.
  5. If you cannot select the socket the fax machine is connected to when configuring it, another telephony device was already configured for that socket. Delete that device first.
  6. If the fax machine is connected to the 'FON S0' socket on the FRITZ!Box, during setup you will be shown which phone numbers to assign to the fax machine. If the fax machine is connected via an ISDN phone system, you must assign the phone numbers to the port on the ISDN phone system that the fax machine is connected to.