At the dawn of the modern era of telecommunications, the underlying SS7 protocol was a marvel of modern engineering. For decades, it was the technology underneath almost every phone call, routing conversations securely and efficiently across the planet. And then, almost overnight, everything changed. The Internet converged with the phone system. This happened very fast and caused serious problems. These days, SS7 is the bane of every telecommunications engineer's existence and is often the root cause of poor telecom security. In this talk, TProphet will take you around the world and across the telecommunications landscape to explore the past, present, and - hopefully - future of the phone system.