| 摘要 |
The mobile telephone system employs a fleet of satellites and a set of gateway ground stations arranged around the globe for handling communications to and from mobile communication units such as mobile telephones. Signals are transmitted between a subscriber unit and the nearest gateway via one or more of the satellites. The gateway is connected to a set of individual service providers such as local telephone systems. The individual service providers may be constrained for various reasons such as contractual or other legal constraints to handle communications only from subscriber units located in certain geographical areas such as within only certain countries or portions of countries. For a mobile communication from a particular subscriber unit, the gateway selects a service provider capable of handling the communication. In one implementation, the selection is based upon the location of the subscriber unit and upon any preferences specified by the subscriber unit. In other implementations, the selection is based on other parameters such as the altitude, speed or velocity of the subscriber unit or the time of day or date upon which the communication is initiated. |
