Phone calls are about to get the HD treatment

Take a phone call today, and the quality of the sound will be the same as it was a few decades ago: sometimes fuzzy, sometimes muffled, with a tinny, robotic characteristic to it. But a few short years from now, you're going to notice a big difference in the quality of your calls.

That's because engineers are working on shifting the country's telephone infrastructure from copper wiring -- the old technology that dates back to the days of Alexander Graham Bell -- to fiber optic cables that can support a lot more traffic. "More traffic" doesn't just mean more calls. It means those calls can be packed with more data, allowing for richer sounds. The traditional phone call uses audio frequencies ranging from 300 Hertz to 3.4 kiloHertz. The HD voice network, or HDN, is expected to allow audio frequencies as high as 7 kHz or more. For the end user, the experience will be akin to upgrading from ordinary TV to HDTV.