About Sim card

Now a days many sim cards avaiable in market . But so many doesn't know ABBREVATION of SIM card and how it operates. SIM->SUBSCRIBER IDENTITY MODULE. it works as follows...When the Mobile starts up, it obtains the IMSI from the SIM card, and passes this to the mobile operator requesting access and authentication. The Mobile Equipment may have to pass a PIN to the SIM card before the SIM card will reveal this information.The operator network searches its database for the incoming IMSI and its associated Ki. The operator network then generates a Random Number (RAND) and signs it with the Ki associated with the IMSI (and stored on the SIM card), computing another number known as Signed Response (SRES_1). The operator network then sends the RAND to the Mobile Equipment, which passes it to the SIM card. The SIM card signs it with its Ki, producing SRES_2 which it gives to the Mobile Equipment along with encryption key Kc. The Mobile Equipment passes SRES_2 on to the operator network.The operator network then compares its computed SRES_1 with the computed SRES_2 that the Mobile Equipment returned. If the two numbers match the SIM is authenticated and the Mobile Equipment is granted access to the operator's network. Kc is used to encrypt all further communications between the Mobile Equipment and the network. IN THIS WAY SIM CARD WILL BE ACTIVATED.