This study investigates the customer satisfaction based on the various levels of many factors such as age, sex, period, motive, preference between wired and mobile service, frequency, and time. Customer satisfaction is measured by 13 dimensions. MANOVA reveals that preference between wired and mobile commerce service, mobile service frequency, mobile e-mail service frequency, wired Internet usage frequency, and mobile Internet usage time have a significant effect on the overall satisfaction. Transmission speed, fare, and ease of operation of mobile Internet service turn out to be improved for better customer satisfaction, the IMT-2000 service in particular.