In recent years, fixed-mobile convergence (FMC) has gathered much interest in the telecommunications industry. FMC is expected to offer benefits for network and service operators as well as end-users. Integrated operators (who own both fixed and mobile networks), are keen to exploit these benefits in order to save costs and generate new revenues. However, such operators are also faced with the challenge of identifying an appropriate roadmap for FMC migration in order to prevent substitution effects or conflict of interest among their own fixed and network operations. In this paper, we present results and analysis of an FMC migration case study for an integrated operator in a Western European market. The additional benefits achieved by the operator are quantified, with suggestions for migration strategies. Results of the study show that an integrated operator can benefit from cost savings, customer retention and prevent revenue erosion by migrating to FMC.