To join the Birthday Program, simply fill in your birthday information at sign up or edit it after logging in: go to Account Settings -> Edit Your Account Information and fill in the fields referring to your birthday.
Every dollar you spend you get $ back. For example, for each $20 spent on phone cards, you will instantly receive 10 Nobel Points. If you spend $50, you will receive 25 Nobel Points, and so on. The more you call, the more free calling credit you receive!