MOBILE COMMUNICATION SYSTEM, METHOD FOR ESTABLISHING CONNECTION OF CALL, GATEWAY UNIT AND COMMUNICATION TERMINAL

摘要

PROBLEM TO BE SOLVED: To provide a mobile communication system and its call connection establishing method in which utilization efficiency of network resources is enhanced by removing generation of a redundant routing. SOLUTION: In a mobile communication network having a plurality of sub- networks each provided with a gateway unit for connection with an UP network, a gateway unit receiving a connection request from a calling communication terminal at first transmits a gateway identifier indicative of a gateway unit provided in a sub-network where a called mobile communication terminal is located to the communication terminal requesting the mobile communication terminal of the mobile communication network to connect a call through an IP network. The calling communication terminal switches the communication terminal requesting connection based on the gateway identifier and requests the gateway unit in the sub-network where the called mobile communication terminal is located to connect the call directly.