Mobile terminal apparatus and hand-off method thereof

a bA mobile terminal that ensures smooth, continuous communications sessions even when in transit, regardless of base station capabilities and functionalities, in a packet-switched data communications network. With this terminal, each of a plurality of lower interfaces - to -M, when its associated access mechanism is in an active state, can obtain a connection to packet-switched data communications network using its home-address HoA. or its care-of-address CoA.BS. When lower interface -loses its connection obtained using the care-of-address CoA.BS, multiple access decision unit instructs mobility support unit to set up a binding of the home-address HoA. and either one of the home-address HoA. and the care-of-address CoA.BS of another lower interface -. Mobility support unit sets up the binding according to the instruction from multiple access decision unit