FRITZ!Box 7430 – Service - Knowledge Base

FRITZ!Box 7430 – Service

Cannot send or receive faxes with external fax machine

Although you configured the fax device according to our guide and can conduct calls over the FRITZ!Box, you cannot send or receive faces. Faxes cannot be transmitted or transmission is aborted. One of the following error messages may be displayed in the event log of the FRITZ!Box:

  • "Not Acceptable Here (488)"
  • "Unsupported Media Type (415)"
  • "Not Acceptable Here (606)"

Important:Some of the settings described here are only displayed if the advanced view is enabled in the user interface. The configuration procedure and notes on functions given in this guide refer to the latest FRITZ!OS.

Simply proceed as described below. After each measure, check whether the issue persists.

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

2 Checking the event log of the FRITZ!Box

  1. Click "System" in the FRITZ!Box user interface.
  2. Click "Event Log" in the "System" menu.
  3. Select "Telephony" from the drop-down list.
  4. Check whether one of the following error messages is displayed for a failed fax. If this is the case, note the information that correspond to the message.
  5. If the message "Unsupported Media Type (415) is displayed, then your provider does not support the requested codec or generally does not allow fax transmission.
    • If the message "Not Acceptable Here (488 or 606)" is displayed, then your provider does not support the T.38 standard. Without T.38 (Fax over IP), fax transmission over the Internet is not reliable.

3 Reconfiguring the fax machine

  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 button (delete) 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 extension the fax device is connected to when configuring it, then another telephony device has already been configured for the extension. You must delete this device first.

4 Testing different remote sites

  • Test whether you can send a fax to or from different fax machines connected to different telephone lines.
    • If fax transmission only fails with a particular line, then the fax machine at the remote site is either not ready to receive faxes or incorrectly configured.

5 Testing different transmission speeds

Many fax machines allow you to select from various transmission speeds (4800, 7200, 9600, 14400 and 36600 Baud):

  • If your fax machine offers this option, test different transmission speeds one after another. The FRITZ!Box supports fax transmission speeds of up to 14400 Baud.

    Note:You can find information on configuring the transmission speed in its manual, or consult its manufacturer directly.

6 Enabling the error correction mode (ECM)

Using the error correction mode (ECM) with your fax machine can considerably improve the results, as long as the remote machine also supports ECM. However, in some cases the results are worse:

  • Enable the error correction mode (ECM) in your fax machine for testing purposes. Refer to the device's manufacturer for information on how to configure ECM, for example consult the manual.

7 Checking whether T.38 was used for fax transmission

  1. Click "Telephony" in the FRITZ!Box user interface.
  2. Click "Telephone Numbers" in the "Telephony" menu.
  3. Click on the "Voice transmission" tab.
  4. Look for aborted faxes under "Display table on completed telephone calls" and check whether "T.38" is displayed in the "Coding" column for these faxes:
  5. If "T.38" is displayed, then T.38 was used for the fax transmission.
    • If "T.38" is not displayed, then T.38 was not used. Without T.38 (Fax over IP), fax transmission over the Internet is not reliable.

      Note:If your Internet telephony provider does not support T.38, then you can use an Internet number of an Internet telephony provider that does support T.38 to receive faxes.