In Korea, the mobile telecommunication service market is expanding rapidly and becoming more competitive. For service providers in such a dynamic environment, it is very important to accurately forecast demand including market potential in order to work out marketing strategies. In this paper, we suggest a general approach to forecast the market potential using a multinomial logit model, which is applied to individual-level market survey data. Then we develop a dynamic market potential model that can adapt to changes in the external environment without requiring further market survey. The proposed model is applied to the mobile telecommunication service market in Korea.