On May 10, 2017, at the Paris G.fast Summit, John Cioffi will describe a path to a terabit over copper. That is not a typographic error, although John's ideas are far beyond the state of the art. G.fast using 106 MHz is now reaching a gigabit. 212 MHz is soon to ship, with correspondingly high data rates. Alcatel has pushed into higher spectrum to demonstrate 10 gigabits. Physicists and astronomers work with submillimeter waves from 300 GHz to 3 terahertz. Nothing like that is used in communications
Wireless systems use much higher frequencies. 28 GHz & 39 GHz 5G millimeter systems are just getting to the field, with millions likely to ship next decade. 70 GHz backhaul systems are in commercial production. Even faster wireless systems are in the labs. Submillimeter waves begin at 300 GHz and go up to 3 terahertz. While speeds like that have not been used in communications, they are common in physics and astronomy.