'''Fall back''' is a feature of a [[modem protocol]] wherein [[data communication]] whereby two communicating [[modem]]s which experience [[data corruption]] (e.g. due to line [[noise]], for example) can renegotiate with each other to use a lower-speed [[connection]]. '''Fall forward<''' is a corresponding feature wherewhereby two modems which have "fallen back" to a lower speed because of data corruption can later return to the higher speed if the connection improves.