A dual mode packet phone is provided, comprising a first connector to connect the phone with a data network, and a second connector to connect the phone with a backup network. The phone automatically switches between the data and backup networks in the event that the data network fails to process the call in a timely manner. In a preferred embodiment, the phone is a Voice-over-IP phone, and comprises a voice processing unit, a control unit, a line interface, a data network interface, and a backup switch.