Hollow Railroad
The Hollow Railroad is the Hollow Ones' rumor mill... how they keep in touch. Information tends to show up to the people who need it most by the mystical connections formed within the "Tradition."
It's called the Railroad rather than a Network because Network sounds too much like the Technocracy. Plus, there are plenty of romantic stories that take place on train tracks and it's not the first clandestine method of transport and communication to be called such.
Incognitos, Moles, Soundwave Masters, and Railroad Riders all make heavy use of or facilitate the Railroad, though any Hollower with the right connections can use it.