About Sim card

Now a days many sim cards available in market . But so many doesn't know ABBREVIATION of SIM card and how it operates. SIM->SUBSCRIBER IDENTITY MODULE. it works as follows...
When the Mobile starts up, it will obtain IMSI from the sim card and passes to mobile operator requesting for access and mobile operator will authenticate for authorized access. And mobile has to pass a PIN to the sim card before it will reveal the information. The operator will search the database for the IMSI which came from sim card and also associated Ki.Then it will generate a random number and compute another number with its Ki along with IMSI and generate SRES_1. which is called as Signed response. Then operator network sends RAND to mobile inturn passes to sim card. Then again simcard generate SRES_2 with its Ki and passes to mobile equipment with encryption key kc inturn passes to Operator network who compares SRES_2 with SRES_1 . if two numbers matched then mobile granted access to network. AND Kc is use for further communication process. IN THIS WAY SIM CARD WILL BE ACTIVATED.