Perhaps
iPhone users have a lot of disposable income in any case, given that they're already parting with $600 for the unit, then paying for AT&T call package and (EDGE) data package on top? But perhaps some might be glad of some cheaper calls, especially when roaming?
Jajah have been
quick off the mark to show that their
mobile.jajah.com works just fine on the iPhone Safari browser. Then again it also works on my years-old Treo 600. One great advantage of having only a web portal (and no client software) to drive your telephony system, is that adding new mobile clients should not be a problem.
Of course the iPhone is equipped with Wi-Fi, but whether this can be used for free VoIP calling is at this point only speculation. Certainly, the cellcos linked with the iPhone (AT&T Wireless in the US, in Europe Vodafone, T-Mobile and the Carphone Warehouse as an MVNO) will not want service revenue put under pressure by companies offering VoIP calling and IP-based messaging instead of SMS.