What is EXT on a fax? Definition and usage

LAST UPDATE: March 5th, 2018


‘EXT’ on a fax machine is a port to plug in a phone extension.

It is usually found near a ‘LINE‘ port which is used to connect the fax machine to the phone jack.


Fax machines have an ‘EXT’ port to attach an extra phone or answering machine to the same line (and phone jack).