Global short message delivery services via satellites are considered attractive if the service can be supported to indoor subscribers. In order to establish the communications link, it is required to concentrate high transmission power into a spotbeam even by a Non-GSO satellite system with low Earth orbits. The idea can be realized by a kind of TDMA scheme where only a single spotbeam per satellite is fired at a timeslot in an efficiently scheduled manner. The paper proposes a scheduling algorithm that enables each satellite to concentrate its power into a spotbeam illuminating an addressed area at a prescribed timeslot, while causing no interference with other spotbeams from adjacent satellites, so that a subscriber in the area can easily establish the synchronization and efficiently receive a message addressed to him or her. Some numerical evaluations are given for a 6-hour period MEO system, for example, to demonstrate the effectiveness and performances.