This paper proposes a Time-based Channel Reservation Algorithm (TCRA) suitable for managing handover and call admission control procedures in future mobile satellite systems. These systems are characterized by a high rate of handover attempts which can degrade significantly their performance. Therefore, we propose TCRA, a scheme which guarantees a null handover failure probability by managing the channel through a reservation strategy in the cells to be crossed by the user. Based on the feature that the satellite motion is predictable and deterministic, the scheme tries to maximize the channel utilization and enables the system to handle the most important number of users. The performance of the TCRA scheme has been examined by simulations and compared to the Guaranteed Handover (GH) scheme. The results show the behaviour of the algorithm and its performance.