Mobile communication system with satellite communication hand off capability

A mobile communication system, comprising:

• a public communication network, a terrestrial private communication system connected to said public communication network, and a satellite communication system connected to said public communication network;
• said terrestrial private communication system having a specific communication zone in which said private communication system is capable of providing communication services and including at least one terrestrial radio base station, at least one mobile communication device for communicating with said radio base station within said communication zone and for communicating with said satellite system, and private branch exchange means for performing communication processing between said private communication system and said public communication network such that said mobile communication device is capable of engaging in communication with subscribers of said public communication network through said private branch exchange means;
• said satellite communication system including at least one orbiting satellite station for relaying radio waves through a satellite communication path, and at least one terrestrial satellite ground station for performing communication processing between said satellite communication system and said public communication network;
• said mobile communication system functioning such that when said at least one mobile communication device moves outside of said communication zone and into an area which is not served by any terrestrial private communication system while engaged in communication with a subscriber of said public communication network through said private communication system, said private branch exchange means transfers information relating to said at least one mobile communication device to said terrestrial satellite ground station through said public communication network to cause said communication between said at least one mobile communication device and said subscriber to be handed off to said satellite communication system such that said communication thereafter passes through said satellite communication system instead of said private communication system.