Say hello to the future of mobile technology We know what SIM cards are, but what do they really do? Subscriber Identity Module cards have long been connecting us to our mobile devices and our cellular networks with unique mobile numbers. Time-tested and reliable, to say that they’re an everyday essential is an understatement. Despite the regular SIM card’s importance in the day-to-day, there’s a new player on the scene: the embedded SIM (eSIM). The technology was first introduced in 2013 by GSM Alliance (GSMA), the association of mobile networks and has ultimately laid the framework for eSIMs globally. The first manufacturer to launch a device sporting an eSIM was Samsung with its Gear S2 3F in 2016. The tech didn’t catch on as quickly, though—not until Apple used the eSIM in its Apple Watch Series 3 release.