It's Skype, but for iPhone! It's basically the same as the computer version but it's easier to use it on the iPhone because it already has a mic built in.
Talking with Skype on iPhone has the exact same feeling any normal phone conversation. It's so natural that it wins the computer version hands down. But of course, the other side of the conversation must have Skype as well (doesn't matter if it's from iPhone, PC, whatever).
Just download the App (for free) and use the same login as the computer version! If you don't have an account yet you can sign up via the App itself.
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