Science writer Timothy Ferris has suggested that since galactic societies are probably transitory, then if there is in fact an interstellar communications network, it consists mostly of automated systems that store the cumulative knowledge of vanished civilizations and communicate that knowledge through the Galaxy. Ferris calls this the "Interstellar Internet", with the various automated systems acting as network "servers".
Ferris suspects that if such an Interstellar Internet exists, communications between servers are mostly through narrow-band, highly directional radio or laser links. Intercepting such signals is, as discussed earlier, very difficult. However, the network probably still maintains some broadcast nodes in hopes of making contact with new civilizations. The Interstellar Internet may be out there, waiting for us to figure out how to link up with it.