Error correction mode (ECM) is a feature in a fax. It corrects errors in the fax transmission from bad phone connections.
A common error is in a fax transmission is telephone line noise, which distorts the image of a fax.
If a phone line is noisy, ECM can result in a higher success rate for fax transmissions.
If faxing over a digital phone line (such as a VoIP phone line), ECM is sometimes turned off. It can interfere with a fax over a VoIP transmission.
ECM works in a similar way to how network packets travel over the internet.
With ECM enabled, the fax transmission is broken into small chunks of data. After each piece of data is sent, the fax machine returns a confirmation of whether it was received. Any parts of the transmission that are not fully received are sent again.
- Wikipedia – Error Correction Mode – a quick Wikipedia article with an overview on ECM fax transmissions.
- Houston Chronicle Small Business – What is Fax ECM? – an overview of ECM in fax transmissions. Written for a non-technical audience.
- T38fax Blog – T.38’s dirty little secret (and why it matters) – A discussion on whether ECM should be turned on or off. ECM is often the first option to turn off with a difficult fax line, however sometimes it may be better to leave it on.
- Cisco – Fax Error Correction Mode (ECM) Product TechNote – a technical explanation of ECM in fax and how it works.
- VoIP Mechanic – How to fax over VoIP – instructions on “best practices” on sending a fax over a VoIP phone connection. Includes instructions on changing the transmission speed and enabling/disabling ECM on common fax brands.
- Konica Minolta – Sending a fax after canceling ECM – How to cancel ECM on a Konica Minolta Multifunction printer/fax.
- Lexmark – How to disable error correction mode (ECM) for voice over internet protocol (VoIP) fax troubleshooting – Lexmark’s instructions on how to disable ECM when using a VoIP phone line.
- Brother – I am using Voice Over Internet Protocol (VoIP) and cannot send and/or receive faxes – Brother’s instructions on turning ECM on and off, and when to do so.