Relay services have changed a lot since 1990. At first, the most common relay services were teletypewriter (TTY) and Telecommunications for the Deaf (TDD) devices. These were like phones with typewriters attached. Two people with TDDs could type back and forth to each other. Or, if a person with a disability wanted to call a regular phone (like a pizza restaurant), they could type into the phone, an operator would read the message out loud to the pizza restaurant, listen to the restaurant's answer and type it back to the person with a disability.