This document discusses how mobile app publishers can increase user engagement and monetization through the Calldorado SDK. The SDK allows apps to show caller ID for incoming calls using an "After Call Screen" that displays ads. A case study shows how the Write Snaps app increased revenue by over 300% and active users by 42% by integrating the Calldorado SDK. The SDK can be easily integrated and provides opportunities for in-call and post-call advertising impressions.