A voice browser is a web browser that presents an interactive voice user interface to the user. In addition, it typically provides an interface to the PSTN or a PBX. Just as a visual web browser works with HTML pages, a voice browser operates on pages that specify voice dialogues. Typically these pages are written in VoiceXML, the W3C's standard voice dialog markup language, but other proprietary voice dialogue languages remain in use.
Questions having the voice-browser tag regards the design for and the use of voice browsers.
Reference: Wikipedia - Voice browser