A new VoIP application has been released by fring for consumers with unlocked Apple iPhone handsets.

Customers will be able to gain access to the first ever mobile VoIP solution for "opened" iPhones via a Wi-Fi connection.

Israeli firm fring, which was launched in February 2007, allows consumers to perform instant messaging and make free calls regardless of device, network operator or platform.

The "light, sneak preview R&D version" will enable iPhone users to get an early taste of fring regardless of whether they are on their mobiles, PCs or other internet devices.

fring is expected to launch a full version of the software for all iPhone owners later this year after Apple releases an updated model of the handset.

The special pre-release version of the application is available for download from the firm's website.

Apple chief executive Steve Jobs recently stated that VoIP application use Wi-Fi would be allowed for the iPhone, unlike those reliant on the mobile network.