What is ECM (Error Correction Mode)?

Last Update: August 9th, 2021


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.

How it works

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.

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