A data-only phone is a pipe dream. VoIPo3G sucks (<a href="http://gigaom.com/2010/01/19/iphone-the-lack-of-voice-over-3g-alternative-theory/" rel="nofollow">http://gigaom.com/2010/01/19/iphone-the-lack-of-voice-over-3...</a>) and uses more bandwidth than a  circuit-switched call. Data is temporarily priced lower than voice minutes, but you can expect this to change if VoIP becomes popular. The carriers <i>will have</i> their ARPU; it's just a question of how they get it out of you.