Objectives: This study was undertaken to analyze the difference between the expectation and performance of service quality provided by a medical institution with outsourced employees in charge of telephone booking services at the medical institution, and use the results to establish strategies for efficient outsourcing management tasks. Methods: The data were collected through a self-administered questionnaire survey of 197 employees providing telephone booking services at four upper-scale general hospitals located in Seoul. A paired t-test was used to analyze the difference between the expectation and performance of service quality, and an importance-performance analysis (IPA) was conducted to derive strategies. Results: Among the determinants of perceived service quality, tangibles showed a great difference between expectation and performance and were found to be an area that requires urgent improvements with consistent interest and concern in the IPA matrix. Conclusions: Therefore, there is a need for strategies to prioritize improvement in tangible aspects of service quality for internal customer satisfaction and maintain reliability and assurance.