iCall could be the real thing when it comes to make and receive calls via Wi-Fi through the iPhone. These guys iCall to say that I have a working prototype, but due to developers of Apple app that NDA can not give anyone. In addition, they say that you can transfer an active cell phone call to VoIP without any interruptions in the conversation.
Press the "jump" to view video Hokey have done little to detailing the process. Unfortunately, they can not provide any additional credit for the product, but putting it into a form easily digestible for those unfamiliar with the idea.
Personally, I love the idea, but I gotta wonder what happens when Skype releases its iPhone App? I should mention that iCall offers a App for users of Windows that lets you call anyone for free. Of course do my $ 3 per month Skype habit of seeing faces.