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Knowledge Base document #275

Integrated fax reception fails occasionally or always fails

Although the integrated fax function was set up according to our guide, fax reception fails occasionally or always fails. Either you cannot receive faxes at all, or received faxes are cut off. One of the following error messages may be displayed in the event log of the FRITZ!Box:

  • 'Not Acceptable Here (488)'
  • 'Not Acceptable Here (606)'
  • 'Unsupported Media Type (415)'
  • 'Email delivery failed. [Message]'
  • 'Error while saving the message on USB storage.'
  • 'An error occurred during fax reception. The document was not received or is incomplete.'

Simply proceed as described below. After each measure, check whether the problem is solved.

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

1 Installing the latest FRITZ!OS for the FRITZ!Box

  1. Install the latest FRITZ!OS on the FRITZ!Box.

2 Checking the event log of the FRITZ!Box

Restarting the FRITZ!Box

Restart the FRITZ!Box once. This deletes all of the event messages. If you do not restart the FRITZ!Box and there is already an error message about fax reception in the event log, there may not be another error message the next time an error occurs.

  1. Click on 'System' in the FRITZ!Box user interface.
  2. Click on 'Backup' in the 'System' menu.
  3. Click on 'Restart FRITZ!Box' and then on 'Restart'.

Checking the event log for error messages

After restarting the FRITZ!Box, check whether there is an error massage in the event log the next time fax reception fails.

  1. Click on 'System' in the FRITZ!Box user interface.
  2. Click on 'Event Log' in the 'System' menu and then 'Telephony'.
  3. Check whether one of the following error messages is displayed:
    • 'An error occurred during fax reception. The document was not received or is incomplete': If the entire fax was still received successfully, there is no error and you can ignore the message. Occasional data packets were lost during fax transmission.
    • 'Email delivery failed. [Message]': The fax was not forwarded by email because the incorrect email address was entered for the push service or incorrect login information was entered for your email account. Correct your email account information. Note: If email delivery fails, the FRITZ!Box does not accept fax calls and also does not save faxes internally or to a USB storage device. If saving is enabled, disable email forwarding as long as it does not work.
    • 'Error while saving the message on USB storage': Data cannot be written to the USB storage device. Test a different USB storage device with the FRITZ!Box, preferably a USB memory stick. Note: If saving faxes fails, the FRITZ!Box does not accept fax calls and does not forward them via email. If you enabled email forwarding, disable saving as long as it is not working.
    • 'Unsupported Media Type (415)': Your provider does not support the requested codec or does not allow you to send faxes.
    • 'Not Acceptable Here (488) or 'Not Acceptable (606):' is displayed: your provider does not support the T.38 standard. Without T.38, reliable fax transmission over the internet is not possible.

3 Checking the protocol for fax transmission

  1. Click on 'Telephony' in the FRITZ!Box user interface.
  2. Click on 'Phone Numbers' in the 'Telephony' menu.
  3. Click on the 'Voice Transmission' tab.
  4. Look for the aborted faxes under 'Details on Completed Calls' and check whether 'T.38' is displayed in the 'Coding' column for these faxes:
  5. If 'T.38' is displayed, T.38 was used for the fax transmission.
    • If 'T.38' is not displayed, T.38 was not used. Without T.38, reliable fax transmission over the internet is not possible.

      Note:If your internet telephony provider does not support T.38, for the fax you can use an internet number from an internet telephony provider that supports T.38.

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