[Robert Paulsen]

I tried finding a way to enable Voice of Wi-Fi, but I don't see anything about it in the settings. I tried googling it, but all I can find is references to the 521 -- does that mean Voice of Wifi is a TMO-only feature?

[N_LaRUE]

What you're looking for is VoIP. That's more or less what that is. Just that T-Mo has it as part of some of their plans and you get 'free' calls via wifi.

Just use VoIP or Skype.

[DavidinCT]

There is a app in the store, called "Spare Phone" I think. It's like $3.50, It uses a Google Voice accont to do VOIP (Make calls free over wi-fi), I used it for a week when I was out of the US on a business trip, and it saved me a lot of money (Verizon wanted $0.80 a min and $2 per mb of data), used the Hotel's wi-fi and called my wife and friends every day and it did not cost me a dime....

Great little program if your just looking to make free phone calls over wi-fi...but, google was shutting down services later this year, so it could stop working if they do....Just a FYI...