What Are SIM Readers?

SIM card (Subscriber Identity Module). The user identification module is a smart card that complies with the GSM specifications. The SIM card can be inserted into any GSM-compliant mobile phone to achieve the function of not randomizing the phone number with the card, and the call fee is automatically charged to the cardholder's bill, regardless of the phone.

SIM card reader

sim card reader is a kind of read

Supports GSM and CDMA

At present, mobile phone users store some important phone numbers in their mobile phones.

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6.2.2 Get previous command response data instruction (GET RESPONSE) Length (R): The maximum length of the response data. All command responses are: 0x90 / 0x00 means the command was executed correctly. 6.2.3 Read the byte string instruction (READ BINARY) stored in binary form from the transparent data file. Offset: the offset address of the data to be read; Length (R): the maximum length of the response data. All command responses are: 0x90 / 0x00 means the command is executed correctly; 0x94 / 0x00 is returned, which means that no data file is selected, that is, the directory may be selected instead of a file; 0x94 / 0x08, which is the current directory or data file and instruction Inconsistent, that is, the current data is not stored in binary form; returns 0x98 / 0x04, which means that this operation does not meet the access security rules, and the password authentication fails. 7 SIM card data read-write test The specific steps and results of the SIM card data read-write test are as follows: Step1 The SIM card is powered on and reset first. The principle is to turn on the contacts first and then start the cold reset. If the cold reset fails, start the warm reset. If the thermal reset is also unsuccessful, release the contact and report an error. After a cold or warm reset is successful, the SIM card should output a reset response. The reset response signal obtained in the experimental test is as follows: 0x3B indicates that the protocol is a forward agreement; 0x67 indicates that TB1 and TC1 appear, and the number of historical character bytes is 7; 0x00 indicates that VPP is not required; 0x29 to 0x22 are 7 historical characters. Step2 After the reset is successful, send a directory selection instruction to select the current directory to the GSM directory. The instructions are as follows: 7F20 is the GSM directory address; the SIM card returns: The command is executed correctly, and the response character has 34 bytes. Step3 Send command fetch response data command: 0x22 means that the command returns data up to 34 bytes; SIM card returns: 0xC0 means that the command corresponding to the response data is SELECT; 0x90 / 0x00 means that the command is executed correctly. Step4 Send the directory selection instruction again to select the current directory to the IMSI directory. The instructions are as follows: 6F07 is the IMSI data directory; the SIM card returns: It means that the command was executed correctly, and the response character has 15 bytes. Step5: Send command fetch response data command: 0x0F means that the command return data is a maximum of 15 bytes; SIM card returns: 0xC0 means that the command corresponding to the response data is SELECT; 0x90 / 0x00 means that the command is executed correctly. Step6 After selecting the directory to be operated, execute the read data instruction. Because the IMSI number is stored in binary form, use the binary data read instruction: 0x00 means the data offset address is 0, that is, from the first word Read data at the beginning of the section; 0x09 indicates that the IMSI message has 9 bytes; SIM card returns: 0xB0 indicates that the response data corresponds to the command READ BINARY; 0x08 indicates that the IMSI number has 8 bytes of data; 0x90 / 0x00 indicates that the command is executed correctly. It complies with the coding rules of the International Mobile Subscriber Identification Number (IMSI), that is, IMSI (International Mobile Subscriber Identification Number) = MCC (Mobile Country Number) + MNC (Mobile Network Number) + MSISDN (Mobile Subscriber Number). 8 Conclusion The SIM card complies with the GSM specification, uses a standard contact IC card, and is subject to the ISO7816 standard. Based on the research of the international standard ISO7816 for contact integrated circuit IC cards, this paper proposes a design scheme for the SIM card reader. The specific test steps are given for the SIM card information interaction procedures. Feasibility, the card reader can work stably and reliably.