Yesterday, I flew home via a Delta flight that has WiFi. It's $7.95 or $8.95 for one flight use but with the promo code from now til the end of the year, it's free. So I sent e-mails, surf the internet, listen to Pandora radio on my iPhone and they all works. But when I tried to call a number via Vonage or Skype, it didn't work. It seems like VOIP is blocked on the airplane, not because of technologies or anything, but perhaps the company or airlines that offer WiFi want to make money on VOIP calls in the future.