A wireless transmit/receive unit (WRTU) may communicate using a data flow that is defined according to flow identification information (FII). The WTRU may participate in the transfer of the data flow between access networks of diverse radio access technologies. The WTRU may communicate with a mobility function to obtain access network and mobility policy information. The mobility function may be, for example, an Access Network Discovery Function (ANDSF). The mobility policy information may describe the conditions by which the transfer of data flows between access networks may be permitted.