Call configuration method using change of frequency assignment in mobile communication system

PURPOSE: A method for setting a call through an FA(Frequency Assignment) change in a mobile communication system is provided to retrieve whether an FA has a usable resource if a system resource cannot be assigned to an FA requested for call setting, and to set a call by changing into the FA having the usable resource, thereby efficiently distributing FA resources. CONSTITUTION: If the first FA is selected(S30), a base station assigns a UATI(Unicast Access Terminal Identifier) and transmits the UATI to a terminal(S31). The terminal transmits a connection request message to the base station(S32). The base station checks whether the FA has a usable resource, and decides whether the FA can use the resource(S33,S34). If the usable resource is drained, the base station assigns a system resource to the second FA(S35), and transmits a traffic channel assignment message to the terminal(S36). The terminal senses that the first FA is changed into the second FA to set a call, and sets the call with the second FA(S37). If the call setting is successful, the terminal transmits traffic channel complete, pilot, and DRC(Data Rate Control) information to complete the call setting(S38).