This paper originates from considerations at a terminal at the Grand Port Maritime de Marseille (France) about introducing a truck appointment system. Several questions were addressed, such as: How to design (reservation and cancellation policy) and imple- ment (technology) the truck appointment system? How to dimen- sion it, e.g., how many appointments should be offered over the day? What are the impacts on the terminal’s overall service qual- ity? This paper addresses the last two issues. We propose a new model to dimension the truck appointment system that also esti- mates the impact on the overall service quality. Although the mod- el presented in this paper represents the situation at this container terminal, it can be adapted to other terminals easily.