ANDSF is Access Network Discovery and Selection Function is an entity in EPC ( Evolved Packet Core) of the SAE (System Architecture Evolution). The main function of ANDSF is to assist UE to discover networks like Wi-Fi or WiMax which are non-3GPP networks. So, the main role of ANDSF is to provide rules for connection with the non-3GPP networks. The information provided to a UE by ANDSF includes inter-system mobility policy, inter-system routing policy, and discovery information.
The ANDSF is a server in the network that provides the UE with policies and network selection information. The UE can query the server for information about other access networks, e.g non-3GPP networks which contain the data management and control functions necessary to provide discovery of different functions and selection procedures. ANDSF client, which runs on UE, interacts with the ANDSF server using OMA-DM (Open Mobile Alliance Device Management) protocol over the S14 interface. This interface is an IP-based interface that supports “push” as well as “pull” mechanisms for communication.