You, Eleanor Shellstrop, are dead. You are in cardiac arrest. Your heart has stopped beating, you have stopped breathing, and medically speaking you have died. Not a great start to your day! But worry not: someone has called 999. This talk is the story of that 999 call. This talk, presented by the CAD & Technical Lead at the London Ambulance Service, will describe everything that happens between dialling 999 and getting to hospital, and all of the technology involved in triaging the call, dispatching the ambulance, and helping patients over the phone before it arrives. This isn't a heartwarming human-interest story from the documentaries — this is the full ins and outs of all the systems, processes, and infrastructure that keeps people safe across a major city every day. We'll explore how we use open data to find exactly where you are, exactly how we decide who gets help quickest and who must wait, and how your phone can help save your life. We'll also look at what happens when it all goes wrong, and how we respond to business continuity incidents — after all, we can't just shut up shop if the system goes down. Expect high-level conversations about medical emergencies, but this talk is suitable for all ages.