Bayonne is the free multi-line telephony server of the GNU project. Source code available for LINUX/UNIX targeted towards messaging, IVR with considerable extensibility. Bayonne supports a modular architecture, native scripting and TGI.
Openmind (Freespeech) is a free speech recognition project for Linux. It will be designed so that it can be easily integrated into any application or window manager as well as the KDE and Ggnome desktop environments.
Festival is a general multi-lingual speech synthesis system developed at CSTR. It offers a full text to speech system with various APIs, as well an environment for development and research of speech synthesis techniques.