Captioning - Explanatory text that accompanies the audio portion of a movie, TV program, CD or other multimedia. Chat software - Programs that allow typing of messages back and forth between computer users in real time. Closed captioning - Captioning which requires decoding to be displayed and can be turned on or off. A special amplifier feeds a loop of wire which is fixed around a room or building. Numeric pagers - Receive numbers only.
Callers leave their phone number or numeric code which is then transmitted to the pager.
Open captioning - Captioning which cannot be turned off. Signaling devices - Visual or vibrating alerting systems that indicate certain sounds have occurred such as a door bell, telephone or alarm clock. TTY, TDD or TT machines - Hardware devices with a keyboard and display used to communicate over the telephone system by typing text. Visual redundancy - Software that blinks or flashes a computer monitor to indicate important information that otherwise is only available audibly.