The invention provides for path optimization for routing of a communication session in a network having a plurality of core networks coupled to a plurality of access networks. Both a core network and an access network perform the path optimization by determining a plurality of possible paths to a plurality of target access points to form a target matrix, determining a corresponding route preference factor for each possible path of the target matrix, and selecting, from the target matrix, a possible path having an optimal route preference factor. An overall or complete path, for routing of the communication session, is then determined either by combining the selected possible paths, or by selecting one possible path as a complete path. The route preference factor, for each possible path, is determined based upon various routing variables, such as quality of service, bandwidth for the communication session, route complexity, interconnect cost, routing cost; resource loading, resource availability, and operator preference for traffic biasing.