For every new customer you refer that signs up with call credit, you will get a referral bonus. You can refer as many friends as you want and keep earning free call credit. To start referring friends, sign in to the Otubio app and click on Earn Credit. Your referral code will be displayed to you. Give this code to anyone you refer so you can get your bonus. You can refer directly from the app via email, text, twitter, and facebook. Remember to tell your friends to enter the referral code when signing up for Otubio.