In the '70s, the idea of the Negroponte Switch was presented by Prof. Nicholas Negroponte of MIT Media Labs, which postulated "What is in the air will go under the ground. And what is underground will go into the air.” What did that mean? It meant that communications that were then going through a wire, will be replaced by wireless, and communications that were going through wireless, will start moving through the wire. So we saw television signals reaching home through cables rather than being broadcast over airwaves. And what that shift did, was free up precious spectrum to be used for mobile wireless telephony, which mostly replaced the copper-wire-based telephones.