PBS explains that deaf people use telephone typewriters and telecommunications devices to communicate over the telephone. These devices resemble electronic typewriters and feature a screen that displays text. PBS explains further that telephone typewriters and telecommunications devices are only able to receive calls from similar devices as the calls are transmitted over the phone line as a series of beeps. Telephone typewriters and telecommunication devices are also referred to as "TTYs" and "TTDs."
According to PBS, non-hearing impaired individuals can communicate with deaf people by using free relay services provided by local telephone companies. PBS also points out that there are portable TTDs and TTYs that allow for additional convenience and special devices that attach to standard phones, as well as hearing aid compatible telephones.
The National Association of the Deaf explains that the Americans with Disabilities Act of 1990 mandated telecommunications and relay systems throughout the United States for hearing impaired individuals and individuals with speech impairments. Relay services are provided at no cost to all relay users.
According to the National Association of the Deaf, relay services also provide emergency access to 911 call centers, and new technology allows for additional TTY and TTD services that include voice carry over, hearing carry over and captioned telephone services. The National Association of the Deaf also advises that there are Internet services that provide text and video relay services.