Both embedded SIM (eSIM) and its logical successor integrated SIM (iSIM) featured at MWC 2023 in discussions and product announcements, attracting greater interest than ever before for IoT devices as well as smart phones. The primary motivation for both is reduction in size, saving precious device footprint, followed by flexibility in the case of iSIM especially. But the need for space saving varies with device size, being acute for some small IoT sensors but less so for handsets and almost nonexistent for some large IoT systems such as vehicles. The two follow a progression, eSIM eliminating the need for a removable SIM at the edge of the device, driven primarily by the increasing desirability of saving onboard space in the…