A technique for assigning an address to a mobile station that is compatible with the layer-2 address on the wireline network which serves the mobile station. The transmitting side terminal includes a packet classifier configured to classify an input service packet as a probing packet or a non-probing packet according to a feature of the service packet, and a packet transmitter configured to transmit the probing packet or the non-probing packet. The serial protocol is defined as a series of pulses distributed over at least one transmission frame.