Two months ago, AT&T petitioned the Federal Communications Commission to plan for the retirement of traditional phone networks. The petition is available at http://www.att.com/Common/about_us/files/pdf/fcc_filing.pdf.
"This telephone network we've grown up with is now an obsolete platform, or at least a rapidly obsolescing platform," Hank Hultquist, VP of AT&T's federal regulatory division, said. "It will not be sustainable for the indefinite future. Nobody's making this network technology anymore. It's become more and more difficult to find spare parts for it. And it's becoming more and more difficult to find trained technicians and engineers to work on it."
"Voice is the most efficient way to communicate," he said. "We have had the same voice service for 80 years. The voice quality you get when you make a call on the iPhone today is the same voice quality Bell Laboratories thought you should have in 1933. Shift forward 80 years, we're still using the same frequency response, 300 to 3300Hz."
You can read more in the ars technica web site at http://goo.gl/Mlnqm.