This morning I've been playing with the prerelease version of Fring's talk software for the iPhone. It enables users to place VoIP calls in place of their plan minutes, giving people a cheap international calling alternative to their carrier's expensive per-minute charges. The one caveat (besides the need for a "jailbroken" handset) is that it requires the thick river of data only available over Wi-Fi, which means you won't be able to make or receive VoIP calls without being in range of a hotspot.
Besides VoIP, the app excels in instant messaging. You can live text chat with buddies on MSN Live Messenger, ICQ, Google Talk, AIM, Yahoo, as well as post and read messages to and from Twitter. Fring also lets you do voice chat with MSN, Google Talk, and ICQ.
To instigate a call, you simply have to hit a large green call button after hitting a buddy's name on the Fring contact list (see photo below). There's no minute counter, hold button, or anything else you might be used to with a regular phone--it's just a quick and dirty call that with a good connection sounds downright decent.
The one service I ran into problems with was Skype. The app lets you plug in your Skype credentials and hook up your phone to your account--a move that enables the use of SkypeOut minutes to make calls to landlines. Some of my Skype contacts would show up, but not all of them, even when they appeared online in the desktop application. I also was unable to place an outgoing call to a landline using SkypeOut, despite being able to call up someone on my Skype buddy list using the free Skype-to-Skype connection.
What makes Fring particularly unique is that will run in the background, so you can hit the home button and do something else while the IM and telephony continues to send and receive data. It's something that won't be possible from the apps found in Apple's directory later this year since Apple is not letting third-party applications run as a background process--a stipulation of the iPhone Human Interface Guidelines that were released with the first version of the SDK.
Whether or not this application will be included in Apple's hand-picked directory later this year is doubtful. Giving paying AT&T customers an easy way to save some money that comes out of the pocket of the telecom giant is probably not in Apple's best interest, which is why I think the company released this as a direct download instead of trying to go official channels.