This paper presents a multi-facet requirement assessment approach for specifying and relating potential business-to-customer mobile tourism services. An integrated requirement model of mobile tourism services including search & notification, community, tour-guide, recommendation, auction, and transaction & payment services is formulated and validated. Three surveys are conducted to collect data from tourists, 3G operators, and travel agencies for assessing usefulness, importance, feasibility, and effectiveness, as well as for illustrating structural relationships of these services. Survey results and implications serve as a valuable guidance for helping mobile service providers in the tourism domain to improve their services for meeting customers' needs.