CDMA subscriber identity module
A CDMA subscriber identity module (CSIM) is an application to support CDMA2000 phones that runs on a UICC, with a file structure derived from the R-UIM card. By porting the application to the UICC (Universal Integrated Circuit Card), a card with CSIM, SIM, and USIM can operate with all major cellular technologies worldwide.
Source: Wikipedia — CDMA subscriber identity module (CC BY-SA 4.0)