Provided is a method for communicating performed by a terminal in a wireless communication system. The method comprises receiving a traffic routing configuration from a first access network, the traffic routing configuration specifying a traffic routing criteria for routing and processing traffic, discovering at least one second network entity by searching a second access network, conducting a traffic routing evaluation to determine whether the at least one second access network satisfies the traffic routing criteria, reporting a routing evaluation result to the first access network when the traffic routing criteria are satisfied, receiving a traffic routing indication from the first access network, and processing the traffic based on the traffic routing indication. When the traffic routing indication indicates traffic of the first access network is processed through the second access network, the traffic of the first access network is processed through the second access network.