How does Ringo call back work?
When you place a call using Ringo, we send a call back using your phone's internet connection to our servers. Once this request is placed successfully, your phone's internet connection isn't required any further.
Our servers then receive this request and call you back immediately using a regular phone network. As soon as you answer our incoming call, we'll connect you to the number you wanted to call. During the call, neither you nor the person you're calling requires an active internet connection.