It might be assumed that common features
address only less severe functional limitations, and that people whose
disabilities are severe cannot find products that meet their needs.
This is often true; for example, slightly larger characters or slightly
greater volume may meet the needs of people with mild vision or hearing loss
But it is not the case for a certain set
of access features. The very
presence of the common features listed below generally examples of the
power of redundancy may make products equally accessible to people with mild
or severe disabilities:
Tones indicating functions or status.
Dialed number display.
Caller ID on call waiting.
Visual alert of status.
Variable signal tones.
On-screen operation and activity display.
Keys identifiable by touch (nib, shape, raised letters, etc.).
It is the features that offer improved performance along a continuum that more often serve only consumers with more mild or moderate disabilities. These include volume control, high-contrast displays, and larger buttons.