The paper describes a standard model for customer loyalty evaluation of services based on a continuing relationship with the provider. The relationship terminates when the customer shows a clear unloyalty behavior (switching to another provider or not using the service). Two different dimensions of loyaltyare considered: Behavioral Loyalty and Attitudinal Loyalty, that are analyzed in relation to Trust, Convenience, Overall Satisfaction and Inertia. The methodology is based on the Structural Equation Models