Nokia, Motorola and Google have already been producing dual-mode VoIP mobile phones. I've seen them.
Also, it was first posted via Republic Wireless (one of the first trial/startups) that these phone makers were starting to manufacture a few of these dual mode phones.
As far as who is buying? Not sure, that would be totally speculation on my part. Just in my own personal opinion, Mobile VOIP has always been kind of an undeground technology that not many people followed or picked up on because they were too busy following Samsung and Apple (lol).
However carriers started to take note IMO when Republic Wireless started offering dual mode phones a couple years ago.
TMobile now offers (just started to) Mobile VOIP but you still have the high costs of a plan. iTalk intends to change this.
You are also seeing small software companies come up with their own downloadable software to enable VOIP on certain phones (but according to blogs, this has a lot of software bugs/issues).
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