What is the best iPhone voip app?

So far as I know, the only official (non-jailbroken) one is Truphone. It’s on the App Store and is free (for the app). You get a $4 credit on your account when you sign up so that you can try it out. Seems pretty good to me, but their rates are pretty high (for voip) at about $0.06 per min for USA/Canada. That’s usually around $.02/min for SIP providers. Still much cheaper than your cell provider though.

For Jailbroken phones, there are several. I liked fring because it supported SIP, so you could use any provider. It wasn’t as slick as Truphone, however.

I’d like to see a SIP native VOIP client that could access your internal address book. I’d pay for that. I really want one that will work over 3G/EDGE however, which Apple won’t allow. :(

iCall will have a free app soon that both accesses your address book and can swap cell calls to VOIP with one button. Just wait a bit.

I use http://www.nextiva.com