Interoperability between terrestrial cellular systems and satellite based cellular systems allows handoffs between different cellular systems. A call in progress by a subscriber unit (101) over a terrestrial based cellular system (100) which includes a mobile switching center (MSC) (105a) and a plurality...http://www.google.com/patents/US6157834?utm_source=gb-gplus-sharePatent US6157834 - Terrestrial and satellite cellular network interoperability
