<p>This paper considers the customer’s equilibrium joining-balking behavior in a retrial queue with two-phase service and priority-purchasing. If the arriving customer finds the server busy, the customer can make three choices (joining the orbit, purchasing the priority or balking) based on different levels of the system information. We consider two cases: the partially observable case and the fully unobservable case. The customer’s equilibrium strategy for the partially observable case and the fully unobservable case are derived. Then, an algorithm is developed to solve the optimal fee that maximizes the service provider’s profit. Finally, the influence of system parameters on performance measures, equilibrium joining strategies and the service provider’s profits is illustrated by numerical examples.</p>