Provided is a method for communicating performed by a terminal in a wireless communication system. The method comprises receiving from a first access network a second access network search configuration for searching a second access network, and receiving traffic routing criteria from the first access network. The traffic routing configuration specifies traffic routing criteria for processing traffic of the first access network by routing to a second access network, determining a mobility state of the terminal, searching the second access network based on the second access network search configuration, evaluating whether a second access network entity discovered through the search satisfies the traffic routing criteria, and processing the traffic of the first access network through the second access network entity. The second access network searching and/or the traffic routing criteria satisfaction evaluating is performed based on the mobility state of the terminal that is determined.