You need to be either a registered customer with Get2world (www.get2world.com) or you should use a calling card from Get2world in order to use the App.
You first need to provide your mobile number and then the number you want to call.You can enter the number where you want to call manually or you can directly fetch it from you contacts. After that you first get a call in your mobile, when you receive the call, you will be connected to the destination number.
Internet in your mobile is only required to receive the call . Once your mobile starts ringing, this App does not need any internet.