During the past few years, many people have started to use virtualized eSIMs instead of the classic physical chip card SIMs. Behind the scenes, a rather complex universe of protocols, interfaces, cryptographic operations, trust models and business processes are in operation to make this work. However, like many aspects of cellular technology, the knowledge of the technology behind it is not widely understood. - despite its ferquent use by a large user base. This talk aims to change that, as far ...