I've had some email exchanges recently about a new mobile voip solution from fring.

fring is soon to launch, what they claim is the only PC independent, completely free mobile VoIP service. I'm not sure I'd agree with that claim. I'd argue Skype mobile on a handheld already represents PC independence. And while they don't work on my Treo, there are a couple of viable SIP phone solutions for mobiles that don't requier a PC in any way. Certainly the move toward mobile-only solutions in on the rise and will leade to greater penetration of handheld VoIP.

Fring is in the pilot and beta stage. It's available as a download to your mobile from: http://fring.com/

It’ll offer 100% free calls, with no subscription – users simply pay for the data they use under their existing mobile plans.

fring will work anywhere in the world using local 3G networks, and isn’t Skype or WiFi zone dependent. It also works without any proprietary hardware, and allows users to operate both GoogleTalk and Skype systems.

As this is at an early stage of development, the application will only work on certain mobile handsets including Nokia Series 60 and N series. Currently, 3 users receive the best service, but feedback has also shown good performance on Orange networks.

Since I dont' have or use an Nokia handsets and I'm not on the networks mentioned, I can't do any testing.

Here's a differentiator I see -

fring™, patent pending peer-to-peer Mobile VoIP
technology, is the only PC independent, completely free mobile VoIP service
with no air-time costs, no need for proprietary hardware and no WiFi or
other VoIP network limits.