You have to admit, this is simply a brilliant way to solicit mobile users fed up with their current carrier.

A service that lets users make free mobile phone calls between 3G handsets has been launched this week with a view to replicating the success Skype has had in the fixed-line telecoms market. The service, called fring, is available to early adopters before a full commercial launch around Christmas.
Israel-based fring’s service uses voice over internet protocol, or VoIP, technology to allow free calls between its users. It differs from other VoIP services in that it is available without needing to use a computer or a special mobile handset….Source: news.independent.co.uk