A method and apparatus for interfacing a synchronous core network with an asynchronous radio network in a next-generation mobile telecommunications system is disclosed. The method includes: a) selecting a function necessary to map a synchronous message to an asynchronous message; b) determining whether the synchronous message is to be transmitted to the mobile station or not; c) storing information necessary to map the synchronous message to the asynchronous message if the synchronous message is to transmitted to the mobile station, d) mapping parameters in the synchronous message to those in the asynchronous message, thereby generating the asynchronous message; e) discarding the message not to be transmitted to the mobile station after storing parameters included in the message not to be transmitted onto a predetermined device; and f) transmitting the asynchronous message to the radio resource controller.