A system and method is provided for transmitting signals ultrasonically among a network of implantable and wearable biological devices. The devices includes one or more implantable nodes, which include a sensing and/or actuating unit, at least one gateway node, and at least one access point node. Ultrasonic signals can be transmitted through the body by the implantable nodes to and from the gateway node, for transmission to and from the access point node. The access point node can be connected to the Internet. In this manner, remote instructions can be transmitted to the implantable nodes and data obtained at the implantable nodes can be transmitted to remote sites.