Relay services allow people with communications disabilities to interact with voice phone users through a keyboard or other input method.
There are various types of relay service. Telecommunications relay service  is a telephone service that allows people with hearing or speech disabilities to place and receive telephone calls. Telecommunications relay service is available in all U.S. states and territories for local and/or long distance calls at no additional cost to the consumer.
Video relay service  enables people with hearing disabilities who use American Sign Language to communicate with voice telephone users through video equipment, rather than through typed text. IP relay allows people who have difficulty hearing or speaking to communicate through a traditional telephone system. IP relay is accessed using a computer and the Internet, rather than a TTY and a telephone.