This is the software publisher's description.

Gizmo Project uses your internet connection (broadband or dial-up) to make calls to other computers. With the click of a mouse, you're connected to friends, family and colleagues anywhere on earth. It's just that simple. For as long as you want and for free.

Any call to another Gizmo Project user is free. No matter when, no matter where, no matter how long. There's no monthly service charge, nor a set up cost.

The only calls you could ever have to pay for are calls to offline phones, i.e. mobile phones and landlines. But with Gizmo Call Out credits these calls are cheap and easy to administer.

Gizmo Project is a competitor to Skype and worth testing, if you seek an alternative.