Since the introduction of smartphones in South Korea, users have shown quick and positive responses to them. This study explores issues in user satisfaction and develops strategies for user retention of a specific mobile telecommunications service provider in Korea. We presented a face-to-face questionnaire to 4398 participants representing nationwide characteristics of Korean users. Mobile telecommunications services and features were divided into two factors based on benefit segmentation and were analyzed with user profiling. Users’ responses to mobile telecommunications services were characterized as “Fundamental services and functions,” which meet users’ basic and traditional expectations for a smartphone as a communication and media tool, and “Cost and monetary benefits,” which mobile telecommunications providers offer to attract users. Based on the scores for those two factors, we divided respondents into five groups and addressed their characteristics in terms of demographic features, subscription duration, and factors that influence user satisfaction. The results of our analysis suggest strategies mobile communications providers can develop for each segment to promote high satisfaction and increase user retention. To improve satisfaction levels, relatively more efforts need to be invested in the fundamental services and functions.