Many deaf, hard of hearing, and hearing impaired people who can no longer use a conventional telephone, are using a TTY, also known as a TDD, with the relay system known as voice carryover or VCO. When using this system, the TTY user is able to read the response of the person at the other end of the line, which is typed by the relay operator. When it comes time for the TTY user to respond, he or she can just speak the way they normally would, and their voice is then heard directly by the party at the other end.