A mobile wireless terminal includes a first wireless unit, a second wireless unit, an audio codec, and a processor unit. The first wireless unit is configured to connect to a wireless relay coupled between the mobile wireless terminal and a phone network over a short-range wireless link. The second wireless unit is configured to connect to a cellular network over a long-range wireless link. The audio codec is configured to process the voice communication. Further, the processor unit is coupled to the first wireless unit and the second wireless unit, and is configured to make a voice communication using the second wireless unit with an external party via the cellular network over the long-range wireless link. The processor unit is also configured to register with the wireless relay to establish the short-range wireless link and, when the registration is successful, to switch from the second wireless unit to the first wireless unit to carry the voice communication with a phone network via the wireless relay.