There are also TTY's that connect directly to the phone line. You don't need to put the handset on them. The most common use for Relay Service is for communication between a person who is Deaf and a person who is hearing. The Deaf person uses a TTY and the hearing person uses an ordinary telephone. Either person then calls Relay service and asks to be connected to the other person.
Relay service is also useful to people with a speech disability .
The person can communicate with Relay service via a TTY or a specialized communications device with text output. Often the person's communication device has its own synthesized speech output, which the person could use instead of Relay service. However, synthesized speech is sometimes hard to hear over the phone. Also, relay may be good for calls to strangers who might reject the call because they are unfamiliar with synthesized speech, the CA can help explain the situation and keep them on the line. Some Relay services also offer Speech to Speech service specifically for people with speech disabilities.