We present a deployable scheme that achieves seamless handover in the context of heterogeneous wireless access networks based on concurrent multipath transfer (CMT) using the Stream Control Transmission Protocol (SCTP) with off-the-shelf Android smartphones and protocol translation servers. Since the scheme is accomplished by neither embedding special modules nor relying on super-user (root) privileges on off-the-shelf Android smartphones, it has considerable potential for general acceptance. In our scheme, we modified the mechanism of the dynamic address reconfiguration (DAR) extension of SCTP to ensure seamless handover, especially for the scenario where the mobile users frequently join/leave heterogeneous Wi-Fi networks that provide Internet access via network address translation (NAT) devices. We confirmed the feasibility of the scheme through prototype implementation.