In one implementation, a communications apparatus includes a communications circuit including a first communications system configured to communicate with a first communications network over a first communications medium; a second communications system configured to communicate with the first communications network over a second communications medium; and a communications port configured to communicate with a second communications network. The communications apparatus can further include a power circuit that includes a first power system configured to power the communications apparatus with a first power source; and a second power system configured to power the communications apparatus with a second power source. The communications apparatus can further include a processing system configured to be powered by the power circuit and selectively control communications flows between the communications port and at least one of the first communications system and the second communications system.