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Knowledge document #108

Setting up an external fax in the FRITZ!Box

You can use a fax machine connected to an analog extension (for example FON 1) or the jack for ISDN devices (FON S0) of your FRITZ!Box to send and receive faxes over the internet.

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

1 Enabling fax transmission with T.38

If you use an internet telephone 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 "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 "Fax transmission using T.38".
  6. Click "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 telephone system:

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephony Devices" in the "Telephony" menu.
  3. If the fax machine is already displayed in the list of telephony devices, click the (Delete) button for the fax machine.
  4. Reconfigure the fax machine: Click 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.
  6. If the fax machine is connected to the "FON S0" socket on the FRITZ!Box, during setup you will be shown which telephone numbers to assign to the fax machine. If the fax machine is connected via an ISDN telephone system, you must assign the telephone numbers to the port on the ISDN telephone system that the fax machine is connected to.



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