VoIP company fring has announced what it's calling the world's first publicly available mobile VoIP app for the iPhone, putting the beta version out for download.  That means they've beaten rival Jajah - who recently announced their intention to release an iPhone VoIP client over the Summer - although Jajah are using the official SDK to develop their software whereas fring currently requires a Jailbroken or otherwise hacked "open" handset.  The client uses WiFi for VoIP calls, rather than the EDGE data connection, in response to AT&T's classification of VoIP as a "conference call service" contrary to their contract.

Developed in conjunction with the Holon Institute of Technology academic research labs in Israel, calls between fring clients (which are already available for handsets running Symbian 8 or 9, Windows Mobile 5 or 6, or UIQ) are free while those to landlines and mobiles are apparently priced competitively compared to AT&T's own tariffs.  Instant Messaging has also been included, and the fring client is compatible with Skype, MSN, Google Talk, ICQ, Twitter, AIM and Yahoo! contacts.  Obviously since this is still a R&D app there could be some bugs present, so fring are looking for feedback and suggestions.

You can install the fring VoIP client through Installer on your iPhone.  Add http://fring.com/iphone.xml as a source and the app should show up among the options.  As ever, if you do try it out, let us know how you get on on in the comments!

[via SlashPhone]