As technological advances are made in the world, communication needs tend to extend with the technology available. Mobile communications has potential for very rapid growth. Many companies are participating in ventures, experiments, and developments that will expand mobile communications services globally. At the University of Maryland, Center for Satellite and Hybrid Communications, a component of Institute for Systems Research, through research these efforts are being facilitated, particularly in the area of Hybrid Cellular-Satellite Communication Networks. This paper discusses progress made in cellular systems, satellite systems, and the networking between them. The functionality of the cellular system and the satellite system is explained, followed by a description of a simulation study involving the hand-off aspect between the cellular and satellite systems. Within the description of the simulation study, the system roles and relationships are described. The simulation study is specifically for monitoring the performance and operation of the Cellular Radio Telecommunication Intersystem Operations IS-41.2-B protocol, used for handoffs in cellular systems, in a hybrid system environment. The main performance issue at hand is the delay to setup a call handoff. The study serves also for developing a model in which a hybrid network intersystem operation can be studied. Final results show the types of analysis that the model can be used to determine.