RollCall is a mobile app that allows users to easily plan and organize social events with their friends. By integrating with the user's phone's address book, RollCall enables users to invite friends directly from their contacts. The app utilizes text messaging and the mobile web to coordinate and rally friends together, ensuring that users never miss an opportunity to hang out with their friends. With RollCall, users can RSVP on the go, making it convenient and efficient to plan get-togethers and meetings with friends using their mobile phone.