The public switched telephone network has seen better days. With interest diverted to the Internet and mobile services, the venerable PSTN that we know and love seems like it's ready for the knackers. But maybe that's not quite right. True, the dominant carriers have let their wireline networks rot, and the TDM technology that seemed so advanced two decades ago is this year's black-and-white TV set. But the PSTN has undergone many rounds of evolution, from cord switchboards to Strowger dial to common control to analog ESS to digital. Now SIP signaling and IP networks are taking over. It's the big carriers who want to claim that this is no longer the PSTN so that they can get out of their regulatory obligations and exercise their remaining monopoly muscle. And the folks in Washington who are supposed to be supervising this still haven't figured out what VoIP is, so no wonder it's all such a mess. Let's see where the PSTN is going and what that means to us.