A gateway for interconnecting different networks includes a network access means for interconnecting a first network that provides a wireless access function to a mobile station with a second network that provides a network access function to the mobile station. The gateway further includes a first tunnel establishment means for establishing, in the first network, a first tunnel between the gateway and a base station accessing one or more mobile stations via wireless communications, for transmission of different packets to the respective mobile stations. The gateway further includes a second tunnel establishment means for establishing a second tunnel between the gateway and the second network, for packet transmission, a tunnel-mobile station connecting means for connecting the first tunnel with the mobile station, and a tunnel-to-tunnel interworking means for interworking the second tunnel with the first tunnel.