Vonage, Lingo, and Philip Greenspun
Checking in on Philip Greenspun's blog, I see that he has a long, long writeup on his experiences trying Lingo, Vonage, and Packet8. If you're not familiar with Philip (I know him only through his writings), he's a brilliant and occasionally bilious computer scientist, teacher, entrepreneur, photographer, pilot, dog lover, and more than credible observer about how technologies are implemented.
His VoIP review is not encylopedic, and he doesn't pretend it is. But it is smart and well-documented. And if I were associated with Vonage or Lingo, I'd be losing some sleep over his reports on customer service (on the other hand, he gives higher marks to Packet8).
"... My first inkling that Vonage might be troublesome came when they lost my FAXed request to port my home phone number. I sent the second request on December 8, 2004. By March 7, 2005 they still hadn't transfered the number so I called them up, waiting more than 30 minutes in queue, and cancelled my request for the transfer. The tech support guy said that they'd been backlogged and that they hadn't been able to port anyone's number for many months. ..."Between the lines, he's drawing a portrait of companies running way too fast to maintain a high-quality experience for customers.