A plurality of disparate communication network systems communicate with each other through the use of different physical media protocols. Each of the systems has at least one input and one output. A message routing system couples a transmitter at any one system input to a receiver at any other system output using a message format that is structure independent of the location of the receiver in the system. Each receiver/transmitter device coupled to any one system input has a unique, fixed and unchangeable identification code regardless of the communication network system to which it is connected. To couple a message from any one receiver/transmitter device to a second receiver/transmitter device at an unknown location within the communication network system, a message format is transmitted from the sending location containing the fixed, unique identification code of the receiving station. A routing system having a plurality of intermediate routing devices receives the message format and couples it to the receiving station at the unknown location using only the fixed, unique identification codes of the transmitting and receiving stations and the addresses of the intermediate routing devices for determining routing.