I’m not endorsing the concept of jailbreaking your iPhone as there are alternatives like the Nokia N and E series that let you accomplish this without doing anything at all but a new piece of software for jailbroken iPhones lets you trick your handset into thinking 3G is WiFi.
That means you can now use VoIP apps like Fring and Truphone over 3G.
I’m using both an iPhone 3G and a Nokia E65.
After multiple attempts, I finally found a FAQ (in French) that told me how to configure the SIP client on my E65 to work with my Asterisk box in the office.
I’ve only gotten it to work with Asterisk and that is only over WiFi. To date (mind you, I’ve back-burnered my efforts since), I’ve not found a way to get it to work over 3G.
Thanks for iPhone tip, can’t wait to try it.
6GB data plan = a lot voip minutes :O