With the increasing competition on the market, customer loyalty has become a decisive factor for long-term business profits. At its high, customer loyalty connotes the high entry barriers the competitor faces when entering the market, and it contributes significantly to a reduction of marketing costs. To attract new customers, companies are required to invest a lot of time and money which can result in uncertainties and risks over longer periods of time. The number of loyal customers as a sign of market share is more significant than the total number of customers. More loyal customers translate to high profits. Loyal customers will continue to purchase or receive the product or service from the same enterprises, and they will be willing to pay higher prices for the quality products and first-class services, thereby increasing sales revenue. Consequently, the focus of many enterprise managers at this point is on marketing management aspects to improve customer loyalty in order to gain the competitive advantage in the face of fierce competition. The importance of customer loyalty has been identified by many researchers and academics in the past years. This importance is also predominant in the telecommunication industry and, consequently, the Nigerian telecom industry. This book attempts to assess and analyze the variables that influence a mobile phone subscriber's loyalty and how Nigerian service providers can enhance this loyalty. The study is based on a survey that uses the quantitative approach. A structured questionnaire was developed and personally administered to a sample of University of Ilorin students across four major GSM operators in the country. Four hundred (400) respondents were sampled through a stratified random sampling. Out of this, three hundred and forty-eight (348) copies of the questionnaire, constituting an 87% response rate, could be used for the analysis. Of the eleven (11) operational factors that were used to assess loyalty of customers in