Have you ever wondered how your cellphone actually works? Yes, there are cell towers, big antennas, huge buildings with lots of cables inside. But what is the magic that makes everything work every day on a million user scale? This talk aims to keep a less theoretical and more pragmatic approach, explaining the practical aspects of LTE networks. The presentation will begin with an overview of specific binary protocols, detailing some of the main network functions, and eventually delving into the key role of both DNS servers and Diameter protocol. Hopefully, at the end, everybody should be able to go home and fire up their own personal LTE network in a box with Open5Gs open-source core implementation.