Hey Bloggers, I'm here today with interesting topic. It is nothing but how SIM card works.
SIM is a abbreviation of Subscriber Identification Module. First SIM was developed in the year 1991. First GSM mobile phone has been sold with SIM card in 1992.
Note: Largest manufacturer of SIM cards in the world is Gemalto company.
Let us know what are the things present inside the SIM and how it is identified and connected with Phone;
At first when we insert a SIM to mobile phone it reads the IMSI (International Mobile Subscriber Identity) number present in the SIM card and it transfer to the mobile operator for authentication. Later the operator provides the authentication key.
It has small chip called Microcontroller and made up of silicone and plated with gold or other conducting metals to help it keep contact with the phone. Chip contains processor + memory + Security Circuits. When comes to memory it has ROM size 64KB to 512KB, the RAM size is between 1 KB to 8 KB and the EEPROM is sized around 16 KB to 512 KB. ROM contains OS for SIM card, EEPROM contains personalized data.
What are all the Key Identification for SIM card?
ICCID: Integrated Circuit Card Identifier , It is the primary account number. It has Issuer Identification number, Individual Account Identification, check digits etc.,
IMSI: International Mobile Subscriber Identity, it identifies the operator's network, it contains Mobile Country Code (MCC) and Mobile Network Code ( MNC) and IMSI number.
Authentication Key (or) Ki : A unique authentication number s stored inside this. It is up to 128bit.
LAI: Location Area Identity, this is nothing but the mobile operator's network is divided into small areas where each area has its own identity. This is stored as LAI when connected to local network.
SMS, Contacts and PUK code all these are present inside the SIM card. And the messages from phone to network are transferred in a secret code, the key to encrypt and decrypt messages is also stored in the SIM.
What is the Operating Voltage of SIM?
operating voltage supported by modern SIM is like 1.8v, 3v or 5v
Types of Microprocessor cards:
yes, the microcontroller chip present on the SIM card is of two types, like
Size Evolution of SIM cards
When SIM card introduced the card size was equal to the size of credit card later it is changed to standard size, and then to Mini, Micro, Nano.
Now the new technology of SIM has been headed in the world, it is nothing but "e-SIM", I will explain about this in next blog so keep follow my blogs to know such interesting things.
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