Basic knowledge of SIM card application skills

SIM Card (Subscriber identity Module), that is, the user identification card, it is a GSM compliant "smart card", SIM card size, large size 54mmx84mm (about the size of the business card), small card size for 25mmx15mm (less than ordinary stamps )。 In fact, the "big card" above really works is it on the "small card", "small cards" on the part of the role of only small fingernails so large. The current domestic popular style is "small card", small card can also be replaced by "kcal" (a Cato can). "Kcal" and "small card" are applicable to different types of GSM mobile phones, early models such as Motorola Gc87c, 308C and other mobile phones are "kcal", now the new models are basically using "small card." The SIM card can be plugged into any GSM-compliant mobile phone, "realize the phone number with the card is not random function", and the call fee is automatically credited to the card user's bill, and mobile phone.

SIM Card Knowledge Advanced

A The data stored in the SIM card can be grouped into the following four categories:

(1) The original data of the system stored by the SIM card manufacturer.
(2) The network parameters and user data injected by the GSM network operation department or other operating department when the card is issued to the user. Including:
* Authentication and encryption Information Ki (one of the input parameters of KC algorithm: Key number);
* International Mobile User number (IMSI);
*a3:imsi authentication algorithm;
*A5: Encryption key generation algorithm;
*A8: The user key (KC) generation algorithm before the creation of the key (KC);
(3) Data deposited by the user himself. For example, short message, fixed dialing, indent dialing, performance parameters, phone count, etc.
(4) The user automatically deposits and updates the network connection and the user information class data in the process of using the card. Includes the location area identification Number (LAI) of the cell phone where the last position was registered, the periodic position update interval set, the temporary mobile user number (Tmsi), and so on.

These data are stored in their respective directory entries, the first type of data is placed in the root directory, when the power is opened first into the root directory, and then according to the instructions to enter the relevant subdirectories, each directory extremely internal data domain have their own identification code protection, only after the check discriminant to the data field data query, read out and update. The first type of data above is usually permanent data that cannot be changed by the SIM card manufacturer, and the second type of data is only allowed to be consulted and updated by the specialized agencies of the network Operations department, and most of the third to fourth class of data allows users to read/write to them using any mobile phone.

Two SIM card structure

(1) The number of phone numbers a SIM can store depends on the capacity of the card's EEPROM (2K, 3K, 8K capacity) and, if there is 8KB storage capacity, the following information can be stored:
*100 Group telephone number and its corresponding sex name text;
*15 Group SMS (short message);
The number recently dialed in the *25 group;
* 4-bit SIM card password (PIN).
(2) SIM card is a chip card with microprocessor, 5 modules, each module corresponds to a function: CPU (8 bits), program memory ROM (6-16kbit), working memory RAM (128-256KBIT), Data memory EEPROM (2-8kbit) and serial communication unit , these 5 modules are integrated into a single integrated circuit. The SIM card requires a minimum of 5 connectors when connecting to the phone:
* Power supply (VCC)
* Clock (CLK)
* Data i/q Port
* Reset (RST)
* Grounding End (GND)
(3) The 20 digit ICCD on the back of the SIM card means the following:
* Top 6 (898600): Is China's code name;
* 7th: Business access number, corresponding to 135, 136, 137, 138, 139 of 5, 6, 8, 9;
* 8th: SIM card function bit: generally 0, now prepaid SIM card for i;
* 9th, 10: code for each province;
*11, 12: The reign of the first;
* 13 bits: Supplier code;
*14-19 bit: User identification code;
* 20 bits: check digit.

GSM Network Logon Step

1. After the cell phone boot will read from the SIM card imsi (15 digits) and Tmsi (4 bytes);
2. Mobile phone login network, will be IMSI or Tmsi sent to the network;
3. The network determines that the IMSI or tmsi valid, to generate a 128bit rand, and then sent to the mobile phone;
4. After receiving Rand, the mobile phone will send Rand to the SIM card;
5. Sim A3a8 the rand with the Ki inside, generating (SRES+KC);
6. Mobile Read (SRES+KC) (32bit+64bit), and sres to the network;
7. The network carries out a a3a8 operation on its own, if the result is the same as the Sres returned by the mobile phone, the user is considered legal.