Some some that email is an infrastructure, others suggest that online multiplayer games are infrastructures, while others might argue that these are sub-elements of the Internet infrastructure as a whole, perhaps loosely classified a communication methods and content, and others might say these are but minuscule parts of the entire communication infrastructure as a whole. Thinking in whole part relationships, network trees or other types of heuristics, the communication infrastructure can be seen to include telephone, television, satellite imagery, radio, publishing, and the Internet. Some would even include transportation into this equation. Overall technology (hardware and code), organizations, standards, policies, the people perhaps actors in the complex infrastructure that is the Internet, which is part of the communication infrastructure.
The unit of analysis is I think scale dependent and part of a boundary setting exercise.