Removable User Identity Module

Removable User Identity Module (R-UIM, usually pronounced as "R-yuim") is a card developed for cdmaOne/CDMA2000 ("CDMA") handsets that extends the GSM SIM card to CDMA phones and networks.

To work in CDMA networks, the R-UIM contains an early version of the CSIM application.

[1] This interface brings one of the main advantages of GSM to CDMA network phones.

This technique allows all three applications (SIM, CSIM, and USIM) to coexist on a single smartcard, allowing the card to be used in virtually any phone worldwide that supports smart cards.

The CSIM application, a port of R-UIM functionality to the UICC, is defined in standard.