This paper investigates factors that influence customers’ intentions to “port” mobile numbers in the Nigerian mobile telecommunications market. The study specifically investigates the effects of service quality, customer satisfaction, switching barriers and multiple SIMs on customers’ intentions to port their numbers to a new provider. A sample of 363, a cross-section of mobile phone subscribers in Anambra State, Nigeria, was surveyed and their responses analysed using simple percentages and descriptive statistics. Regression analyses were used to test the hypotheses, and the results confirm the effects of service quality, customer satisfaction, switching costs and attractiveness of the alternatives on porting intention. The effect of multiple SIM cards was, however, not confirmed. Demographic effects were also found, with age and occupation influencing subscribers’ intentions to port. Implications of the study include that regulatory efforts should be geared towards increasing consumer education on mobile number portability (MNP) and licensing of universal SIM cards to allow porting between operators with short codes. Efforts should also be made to improve service quality and increase brand attractiveness. The paper discusses the contributions and implications for theory, society/policy and managers.