TTY users prefer to connect with IVRs directly. This means that all prompts, menus, and messages must be available in Baudot, the character protocol used in TTY communication.
Some TTYs cannot play touchtones during a call; these users are only able to respond to prompts if they have a standard touchtone telephone connected in parallel. Some IVR systems can receive responses in Baudot or touchtone.
If there is no direct TTY access to the IVR, TTY users will access the IVR through TRS. The relay operator must type all prompts, menus, and messages to the TTY user, who then responds. This transcription-response cycle may exceed the IVR's timeout. Often the relay operator must re-dial the IVR in order to complete the call. Inclusive Technologies has produced a Flash animation of this problem.
A VCO call may encounter the same problem with speech input IVRs. The time given for speech users to receive a prompt, deliver a response, hear a confirmation, and approve the entry may be too rapid for VCO users.
TTY users would benefit from any information displayed, such as visual notification of voice messages.
Some TTY users also have a visual impairment.
All audible materials such as voice mailbox set-up and administration should be available in text form. For example, there should be a text-based method for the user to change a password.
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