Billions of subscribers use SIM cards in their phones. Yet, outside a relatively small circle, information about SIM card technology is not widely known. This talk aims to be an in-depth technical overview. Today, billions of subscribers use SIM cards in their phones. Yet, outside a relatively small circle, information about SIM card technology is not widely known. If at all, people know that once upon a time, they were storing phone books on SIM cards. Every so often there are some IT security news about SIM card vulnerabilities, and SIM card based attacks on subscribers. Let's have a look at SIM card technology during the past almost 30 years and cover topics like Quick intro to ISO7816 smart cards SIM card hardware, operating system, applications SIM card related specification bodies, industry, processes from SIM to UICC, USIM, ISIM and more SIM toolkit, proactive SIM eSIM