Nobody's built a demonstration unit yet, but numerous very respected engineers are impressed by the concept. Using submillimeter frequencies, the telephone binders as waveguides, and massive calculations for "noise cancellation," speeds as high as a terabit should be possible.
Those specifications are at or slightly beyond the state of the art, so building the first unit is still to come. With support, Cioffi believes it can be done in just a few years and commercially soon after. That remains unproven but the industry is alive with enthusiasm. Technical presentation .
Terabit DSL Proposed By Stanford Professor John Cioffi
One Terabit 100 meters, 100 Gigabits 300 meters, 10 Gigabits 500 meters