Customer satisfaction is an increasing challenge for telecommunication companies. In the last few years, the mobile telecom market has witnessed a substantial growth and rapid changes globally, as well as domestically in Nigeria. Customer satisfaction is a critical issue in the success of any business system. The purpose of this research is to evaluate “whether” and “how” ZAIN customers are satisfied or dissatisfied with the customer service provided at ZAIN outlets in Port Harcourt region with the help of service quality by the customers of the outlets. The research would be based mainly on quantitative method; i.e. questionnaire method using service quality and satisfaction attributes, along with literature review and personal interview results to develop the questionnaire. The Service Quality Gap which aims at measuring the customer satisfaction, by comparing their expectation and perception of service after experiencing the service, serves as the theoretical framework for the research. Moreover, SERVQUAL dimensions covering Reliability, Assurance, Empathy, Responsiveness and Tangibles are used in the further development of theory and modelling of the questionnaire for this research.