Fring is making its mark by offering a free application that will allow you to make free calls to your application-compatible cell phone. The company uses a mobile version of VoiIP, called mVoiIP (mobile voice over IP). The fring application is a downloadable mobile application that will allow anyone with a compatible cell phone to converse or chat with other fring, Skype and GoogleTalk users free of charge!
When fring users call over Wi-Fi or 3G mobile networks (instead of GSM) and use only the data within the existing subscription agreement they are not charged for air time, versus the highly priced GSM air time charges.So far, fring is compatible with the following cell phones: Nokia models, 6630, 6680, 6681, 6682, N70, N72, N80, N80i, N90. Some features may partially function in the following cell phones: Nokia N71, N73, N75, N91, N92, N93, E60, E61 and E70.
More details at Pocket Lint