You received a campusSIMS + Mint Mobile SIM card with your I-20 because campusSIMS partners with your school to help you get connected with mobile phone service. campusSIMS provides your school with its SIM cards, and then your school sends the SIM cards to you with your I-20 so that you can get your U.S. phone number before arriving at school. This allows you to use your phone as soon as you land in the U.S.