TTY is a data terminal that users who are hearing impaired or speech impaired can use to transmit and receive text through a telephone system. You can also refer to a TTY as Telecommunications Device for the Deaf, or TDD. A typical TTY resembles the keyboard of a laptop computer with a one-line or a two-line alphanumeric display. When you do not use the TTY to transmit text, the TTY is silent. As a user types on the device, the TTY emits audio tones that the telephone network transmits.
Not all TTY users transmit and receive messages with TTY devices. Approximately half of the users who rely on TTY devices are hearing impaired, but can speak clearly. These users often prefer to receive messages on their TTY devices and then speak in response. You can refer to this process as Voice Carry Over, or VCO.
Messaging offers the Audix TUI, which provides support for TTY users. The Audix TUI supports many of the features and menus of traditional Audix and Intuity Audix systems.
Messaging supports TTY on the TUI caller interface. The TUI caller interface is the part of the code that allows the user to log into the system. After the user logs in, the system presents the Audix TUI menu. The caller interface is currently Aria-like and the administrator cannot change this behavior.
Messaging does not provide automatic TTY support in Messaging mailboxes. You must enable TTY support in the same way that you configure a mailbox to use a spoken announcement set. For the TTY announcement set, you can also specify the conditions under which the specific mailbox uses TTY-format prompts and menus. Regardless of the selected announcement language, users can record TTY or voice messages.
In Messaging, you can configure mailboxes so that callers can select TTY-format, or voice prompting from the same mailbox. Thus, mailbox owners who receive both TTY and voice calls no longer need different telephone numbers and mailboxes for each type of call.
You must be aware of the following issues that can compromise the use of TTY devices on a Messaging system:
You must configure the Messaging system to use the G.711 encoding format. The GSM encoding format works well with voice but distorts the TTY tones. For more information, see Ensure voice quality.
Under certain conditions, the Messaging system does not support TTY with Internet Protocol (IP) integration. For example, the system does not support IP integration when TTY tones transmit across a wide area network (WAN).