Ever since the iPad announcement we have seen one company after another make noise that their application is now able to make calls over 3G. First was iCall. Then along came Fring and today we have 8 x 8 making their's.
What I have yet to see though are any real time reviews that this is working perfectly in a mobile environment. My attempts with 3G VoIP are mixed. If I'm standing still and have really good connectivity the calls work, but when driving, the experience has been less than optimal. Of course this will improve, but I doubt the experience over 3G will come close to my solid experiences in Las Vegas over Clearwire using Truphone and Skype in a series of trials with nothing more than an iPod touch and the native versions of the companies applications and a Cradlepoint travel router with the Clearwire 4G USBdongle. Those experiences, when in motion, were as good as my laptop using Skype and the same 4G dongle.