ROK, a mobile phone provider out of the U.K., has unveiled a mobile VoIP application that aims to cut the cord entirely with service providers. The ROK Viper, the company says, is the first “no strings attached” mobile VoIP application.

With Viper, you can use Bluetooth to connect your mobile to a broadband network, which will enable you to make calls over the Internet. Specifically, you process your calls through a Contacts list, much like an Instant Messenger program: If one of your friends is “online,” then you can put through a call and have a chat. We would presume as well that calls to non-Contacts folks would require you to use your mobile provider’s network.

You’ll need one of a short list of Bluetooth-enabled Nokia handsets. That list of compatible devices is expected to grow quickly.

ROK Viper is a free download, and you can get it here.