high voltage transmission lines can and are built with a glass fibre core, and would be essentaily invisible
also a ditch witch and couple of support vehicles could run cable through most terrain, and in agrairian areas , not needing permits and such, would be indistinguisashable from other activity ,happen very quickly, and leave no trace
humanity has reached the point where our comunications net is a given for 90%+ of the population centers in one form or another, and if not for the slop, would have an order of magnitude, excess capacity. throw in peer to peer ,and the soon to be blanket coverage from sattelite swarms, and well, what? sonar relays for underwater, and seizmo transmitters