Voice Carry Over ( VCO ) phones let individuals with a hearing loss continue to use their own voice on the telephone.
VCO phones allow people to speak directly to the person they are calling, and then read that person's response on their display. No more straining to hear the response, or asking people to repeat themselves. Because you can read their words, the meaning comes through loud and clear every time. And the conversation maintains a personal, natural feeling, because people are using their own voice.
VCO calls with a TTY can be made in two different ways, either directly between two callers or with the help of a Telecommunications Relay Service (TRS) by dialing 711.
A Hearing Carry Over (HCO) phone uses the TRS relay service and allows a mute or speech impaired person who can hear but not speak to listen directly to the standard telephone user’s conversation and respond by typing their text on the TTY. The TRS relay operator will talk for the person who cannot speak.