Free application known as O2 social application in order to enable cheap international calls works with Facebook. After downloading the free application that can initiate calls through Facebook chat cost the same as international calling landlines in theUK only.
Bright, even other people, applications need to install it even better is not proposed.
Closest to the application of social choice O2, which is probably Skype, it is compared to the O2, a nuisance than a configuration in solution. Occasional international call, so that people can do far worse than the use of social O2 and 3G applications can be done to demonstrate considerable success.
O2, the society in the App Store, you may download an application to check this link