MME(Mobile Management Entity): authenticating users with HSS assigning temporary identifiers to the terminals Roaming authorization Serving GW:route packets to and from other 3GPP networks Packet Data Network GW:routing with non-3GPP networks Home Subscriber Server(HSS):subscriber data,authentication and authz,location ◼ MME(Mobile Management Entity): authenticating users with HSS assigning temporary identifiers to the terminals Roaming authorization ◼ Serving GW: route packets to and from other 3GPP networks ◼ Packet Data Network GW: routing with non-3GPP networks ◼ Home Subscriber Server(HSS):subscriber data, authentication and authz, location