A terminal for transmitting a voice signal, comprising: a transmitter having a first transmission module arranged to transmit signals over a packet-switched data network and a second transmission module arranged to transmit signals over a circuit-switched telephony network; a microphone for generating a voice signal; and signal processing apparatus configured to generate a first signal and a second signal from the voice signal, each representing information from the voice signal over a same portion of time. The signal processing apparatus is further configured to supply the first signal to the first transmission module for transmission to a receiver via the packet-switched data network, and to supply the second signal to the second transmission module for transmission to the receiver via the circuit-switched telephony network. There is also provided a terminal for receiving such signals and reconstructing the voice signal, and corresponding methods and program products.