A method of supporting communication using two or more heterogeneous radio access technologies (RAT) comprises: receiving a setup message providing instructions for access to a second base station in a second communication network supporting the second RAT from a first base station in a first communication network supporting a first RAT; and attempting to access the second base station. At this time, when the terminal successfully accesses the second base station, specific traffic type data are transmitted and received through the second base station, and data other than the specific traffic type can be transmitted and received through the first base station.