Voice-only apps without speech recognition

On the wear-hard mailing list, uberborg Doug Sutherland mentions

Developing Voice-only Applications in the Absence of Speech Recognition Technology
http://www.cc.gatech.edu/fce/savoir/pubs/savoir.html

and

Caiviar is an Interactive Voice Response (IVR) System based on CAPI.
It runs on Linux and Windows systems, and supports Text-To-Speech
(most notably Realspeak and Festival), multithreading, Barge In,
3 Party Conference, G3 Fax etc. It has a very simple interface,
allowing fast creation of Telephony applications, like e.g. Voiceboxes,
Authentication systems, automatic Callcenters etc. Languages supported
include Java, C++ and Perl. The source code for Caiviar is freely
available.

http://www.quiss.org/caiviar/

TTS+Caiviar HOWTO
http://www.quiss.org/caiviar/TTS-Caiviar-HOWTO