A method, apparatus and a computer readable record media storing instructions for executing the same method for interfacing among a hybrid type synchronous or asynchronous terminal to a core network in a next generation mobile telecommunications system. The hybrid type synchronous or asynchronous radio network determines the operating type of the core network when the core network has a connection thereto, and sends the determined core network operating type information and information related to the core network to the hybrid type synchronous or asynchronous terminal, thereby allowing the synchronous or asynchronous terminal to smoothly perform a data interfacing operation with the core network.