The operator listens to the voice caller and types what the person is saying into a TDD for the person who is deaf. The operator also reads the typed messages from the person who is deaf to the hearing person. Call your local phone company or check your phone book for information on the relay service in your state. TDD phone conversations can often be cumbersome and time-consuming. Another option to a TDD is a text telephone, which uses an existing computer with a modem.
Text telephones are compatible with TDDs.
Unlike TDDs, which only display one line at a time on a narrow display, messages sent over the text telephone appear in multiple lines on the full computer screen. The messages appear simultaneously as they are being written, making the conversation flow more naturally. A TDD has a keypad for sending messages and a digital display for reading messages from the sender. Telephone Devices for Speech Impairments People with difficulty speaking also often use TDDs. A weak speech handset allows you to raise the volume of your voice, so that others will hear you better.