It seems so simple: 160 characters & 3 API parameters: To=, From=, Body=. How hard could it possibly be? Yet I have spent the past 10 years working on SMS. Our backlog is getting longer not shorter. This talk will explore why SMS is so much more interesting (and much harder!) than meets the eye. We will go deep on both the technical and business challenges with SMS, including examples of the really hard problems that Twilio has solved and the much harder problems that still lay ahead of us.