ViaVoice is a continuous speech recognition program developed by IBM. Mainly it is a MS-Windows program, but IBM brought out a version for Linux in 2000. Several components of ViaVoice should be distinguished:
Required to compile any applications which link to the ViaVoice speech recognition engine. Most notably, this includes xvoice. The SDK is not required to run these applications once they are compiled.
The ViaVoice recognition engine. It is needed for running any application.
ViaVoice Dictation is the product which IBM released in 2000. Apart from the runtime, it includes a java GUI which is used for training the recognition engine to particular speakers, a text field into which text can be dictated, and facilities to correct misrecognitions and to retrain the recogniser on wrong words. The ViaVoice Dictation product does not interface with any other application software, i.e. it is not possible to dictate into other programs than the text field provided by ViaVoice Dictation.
The reverse of the speech recogniser: it converts written text into spoken words. Something like this is always part of any speech recognition software and is used for user interface tasks. ViaVoice Dictation also includes it.