Visual displays of text must be legible even under adverse lighting conditions; visual (or tactile) indications of line status are essential.

A line by line presentation is often preferable to a single line of scrolling text.

Although visual display of text and line status is not automatically required for people with severe speech impairment, it will often be the case that the speech difficulty is associated with deafness. Also, these features are usually associated with text telephones, which provide the keyboard-send feature.