During 2022, sysmocom was tasked by IoT operator Onomondo to develop a software implementation of a rather fully-featured 3GPP USIM (and ETSI UICC). The idea of this project is that one would run it inside an existing trusted execution environment / secure element of an IoT device, removing the need for a physical chip or slot.
After some grace period, this project was released as open source software in 2024. Let's have a look on what it can do and how it can be used.