Brother 'Comm. Error': fax communication failure fix

What causes it

• A VoIP or digital phone line compressing the audio so fax tones are corrupted
• Line noise, a poor extension cable or a damaged wall socket
• The receiving fax machine busy, out of paper or faulty
• The transmission speed set too high for a marginal line
• Other devices sharing the line and picking up during transmission

How to fix it, in order

Work down the list and stop when the printer recovers. The steps are ordered from most likely and least invasive to last resort.

1. Lower the fax transmission speed

   This is the most effective single change on a modern line. Press Menu, then Initial Setup, then Compatibility, and set it to Basic for VoIP, or Normal instead of High. On touchscreen models it is under Settings, All Settings, Initial Setup, Compatibility. Basic caps the speed at 9600bps, which is slow but far more tolerant of a compressed line.

2. Check the phone line physically

   Plug an ordinary telephone into the same socket the printer uses and listen for a clean dial tone. Crackle, hum or a faint tone means the line itself is the problem. Try a different, shorter phone cable and connect directly to the master socket rather than through an extension, since extension wiring is a common source of noise.

3. Confirm whether the line is VoIP or fibre

   If your phone service runs over broadband, which is now the default for most UK and many other providers, fax over that line is unreliable by design. Ask your provider whether they support fax, or whether they can enable a fax-friendly codec. This is the difference between troubleshooting and accepting a limitation.

4. Remove other devices from the line

   Disconnect answering machines, card terminals, alarm diallers and extension telephones from the same line while you test. Any of them picking up mid-transmission corrupts the fax. If removing them fixes it, use a dedicated socket or a filter so the fax has the line to itself during transmissions.

5. Print the transmission verification report

   Go to Menu, then Print Reports, then Transmission Verification, or Fax Journal, and look at the result codes and which page the transfer failed on. A failure that always happens on the same page suggests a document problem; failures at random points indicate line noise.

6. Try a shorter, simpler fax

   Send a single page of plain text to the same recipient. If a one-page fax succeeds where a ten-page one fails, the line is marginal rather than broken, and lowering the speed plus sending in smaller batches is a workable approach.

7. Confirm the problem is not at the other end

   Send the same fax to a different recipient. If it goes through, the original receiving machine is out of paper, busy, or has its own line problem. That is a common outcome and it saves you from rebuilding your own setup unnecessarily.

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