What is ISIM (IMS Subscriber Identity Module)?

ISIM comprises parameters for recognizing and verifying the client to the IMS. An IP Multimedia Services Identity Module (ISIM) is an application residing on the UICC. ISIM conveys data utilized in SIP protocols like IP Multimedia Private Identity (IMPI), IP Multimedia Public Identity (IMPU) and cypher keys (used to encrypt information. It contains client identity and security keys utilized to scramble the data communicated over-the-air.