On the back of the prepaid card there are instructions how to activate the credit so you can call internationally. From my experience, I can say that you will need an account first from where you enter the application that you download for the platforms you have (Windows, Android, Nokia Symbian, etc). Then everything is simple: after you log in, call the number from the back of the card followed by the charge number and then enter the international number where you want to dial. The software allows you to use the Internet to place calls.