SentiVoice – a system for querying hotel service reviews via phone Sentiment analysis or opinion mining is a new research field but playing an important role in computer sciences, attracting interests of academia as well as industry. As a field of research, it is closely related to natural language processing, machine learning, text mining and information retrieval. In this paper, we use the machine learning approach to classify hotel service reviews. The results of this phase are integrated into our voice server system that we have successfully developed previously (, ). As a result, users can consult hotel information via phone calls instead of the keyboard.