SIM card technology is one of the most popular technology which is used in Mobile phones to activate the connection and to communicate and for making links with the server system and also used in various electrical and electronic projects. It is the Subscriber Identity Module that contains the integrated circuit to store the International Mobile Subscriber Identity or IMSI and the keys to identify and authenticate the subscribers on the communication system. The SIM is embedded in a smart card that can be removed and transferred to different mobile phones. SIM card provides security system to users. The first SIM card was made in 1991 by Giescke and Deviant of Sagem communications in France.
The data stored in the SIM card includes a unique serial number called ICCID, International Mobile Subscriber Identity or IMSI, Security Authentication information, temporary information about the network, a Personal Identification Number or PIN and a Personal Unblocking code or PUK for unlocking. SIM card contain it’s internally memory in which stores the data, personal and financial information, identity for GSM/CDMA. Modern SIM cards allow the storage of application data that communicate with the handset or server using the SIM application tool kit. The SIM card stores network specific information to authenticate the identity of the subscriber in the network. Out of the many keys, the most important keys are ICCID, IMSI, Authentication key or Ki, Local Area Identification or LAI, and an operator specific emergency number. Micro sim have been invented for latest mobile phones. The SIM also contains other data like Short Message Service Centre number or SMSC, Service Provider Name or SPN, Service Dialing Number or SDN, Value Added Service or VAS etc. The SIM comes in various data capacities ranging from 32KB to 128K and can store 250 contacts.
Keys of SIM Card:
1.Integrated Circuit Card Identifier or ICCID – It is the Primary account number that has 19 digit long. The number has sections like Issuer Identification Number or IIN, Individual Account Identification, Check digit etc.
2.International Mobile Subscriber Identity or IMSI – It is used to identify the individual operator net work. Normally it has 109 digits. Its first 3 digits represent Mobile Country Code or MCC, the next 2 to 3 digits represents the Mobile Network Code or MNC, The next digits represents the Mobile Subscriber Identification Number or MSIN.
3. Authentication Key or Ki – It is a 128 bit used to authentication of the SIM card on the Mobile Network. Each SIM has a unique Authentication key assigned by the operator during personalization. The Authentication Key is also stored in the data base of the carrier’s network. When the mobile phone first activates using the SIM card, it gets the International Mobile Subscriber Identity or IMSI from the SIM card and transfers it to the mobile operator for authentication. The data base in the operator system then searches for incoming IMSI and the associated Authentication key. The operator data base then generates a Random Number or RAND and signs it with the IMSI and gives another number called Signed Response 1(SRES_ 1). The RAND will be sending to the mobile phone and the SIM then signs it with the Authentication Key and produces the SRES_ 2 which then passes into the operator network. The operator net work then compares the SRES_1 it produced and the SRES_2 from the mobile phone. If both match, the SIM is authenticated.
4. Location Area Identity or LAI– This the information stored in the SIM about the local network available. The operator network is divided into different small areas each having a LAI.
5. SMS messages – SIM card can store many SMS
6.Contacts – SIM can store around 250 contacts.
Functions of SIM card:
The SIM card performs the following functions:
1) It identifies the subscriber: The IMSI programmed on the SIM card, is the identity of a subscriber. Each IMSI is mapped to a mobile number and provisioned on the HLR to allow a subscriber to be identified.
2) Authenticate the subscriber: This is a process, where, using the authentication algorithm on the SIM card, a unique response is provided by each subscriber based on IMSI (stored on SIM) and RAND (provided by network). By matching this response with values computed on the network a legal subscriber is logged on to the network and he or she can now make use the services of the mobile service provider. SIM card is becoming a feature of mobile work.
3) Storage: To store phone numbers and SMS.
4) Applications: The SIM Tool Kit or GSM 11.14 standard allows creating
Applications on the SIM to provide basic information on demand and other
Applications for m-commerce, chatting, cell broadcast, phonebook backup,
Location based services etc.
Microprocessor based SIM cards:
The most important part of the SIM card is its Microcontroller. It is a paper sized chip which is a typical ROM with a size between 64 KB to 512 KB. The RAM size ranges between 1KB to 8KB while the EEPROM size is in between 16KB to 512 KB. The ROM contains the OS or operating system for the card, while the EEPROM contains data called personalization that includes security keys, phone book, SMS settings etc. The operating voltage of SIM maybe, 1.8V, 3V or 5V but the operating voltages of most of the modern SIM support 5V, 3V and 1.8V.
There are two types of microprocessor cards. These cards take the form of either contact cards, which require a card reader, or contact-less cards, which use radio frequency signals to operate.
Types of SIM Card:
There are two types of SIM cards that is GSM and CDMA:
GSM technology stands for Global System for Mobiles and its foundation can be credited to Bell Laboratories in 1970. It basically uses circuit switched system and divides each 200 kHz signal into 8 25 kHz time slots and operates in 900 MHz, 800 MHz and 1.8GHz bands. It uses a narrow band transmission technique- basically Time Division Access Multiplexing. The data transfer rates vary from 64kbps to 120kbps.
CDMA means code division multiple access which explains about communication channel principle that employs spread-spectrum technology and a special coding scheme which are time division multiplexing scheme and frequency division multiplexing scheme.
Aim: to design the gsm sim card reader and to interface it to the pc.
·Ic 74hc04(inverter). (2 ic’s means 8 gates)
·Crystal oscillator. (just one of about 3.5Mhz)
·10k ohm resistor. (10 in number)
·Transistor –bc293c. (3 in number)
·Diode. (3 in number)
·1M ohm resistor
·Rs 232 male or female whichever suitable for the connection.
·Simcard reader port of six pins.
The sim card interfaces consists of the series of the impedance matching circuits as we see there are six pins and there are eight pins some of the sim’s. The termination resistor has a value of 1- 10k ohm for data line & reset line and here we have 1-2k ohm for the clk line.we here build the circuits as per the pin requirements as we see i have connected the crystal oscillator for the clk pin and the requirement is calculated Vsim pin is connected to the DTR of rs232 terminal, then the clk is to the crystal oscillator,these data lines simdata and Vsim terminalthe the RTS of rs232 is connected to the simrst pin ,the circuit shows almost all the pins covered this is done without using any other ic. We can get this in market rarely but as we know the chip is all integrated to the single cable usb line which has max 232 which converts the TTL logic to the computer logic.
The sim connector and the pin specifications of the sim.
Clock circuit :this circuit helps the device to put the data in and out the sim card memory as we have same i/o pin is connected to the tx and rx via the transistor.
DTR terminal: this terminal is used mainly to make the sim ready to the transmit and receive operations and clearly this helps to transmit the data and helps to convey it to the memory of the sim and clearly we get the data done in putting into the sim memory .
RTS:this terminal is used to give the signal to simrst pin of the sim and makes it reset and this is done in the active low state and which also helps the program to start from the beginning for the new process.
Data i/o is only one and this is brought together by the single transistor and there is a possibility more advanced circuit in the place of that and also we can use more than one transistor or any other network analysis.
Installing the software:
The software installing should have a proper sim card accessible driver this helps in the connecting the device to the host i.e your pc.
But first we have to connect the RS232 to the usb and for this i have shown you the writing attached with this article and also we need to search the software properly.
For example we have the software like Simmaster2.0 which is very rarely got in the web also we have Simprobackup,by these softwares we can have backup also we can use it more if the we are smart enough.
Install the proper softare and also see we have the sim connected and we can extract all kinds of the codes of the particular sim in order to do know.
To run the software on your computer system, you require the following minimum hardware and software configuration settings:
Hard Disk Space: 5 MB of Free Hard Disk Space
RAM Recommended: 128 MB RAM
Pentium class or equivalent processor
Operating System Required
Any of the Microsoft Windows OS including:
We can read the data in the sim card of six pin and clearly we can find more usefull codes in it by using suitable software.
Then we need to connect to the rs232 female pin and then convert the signal to the pin of the usb.
Conversion of RS232 to usb port serial
Need for conversion:
RS-232 works on the voltage different than that of the TTL logic. As we see in RS-232 it represents 1 as-3 to -23 and ‘0’ from the +3 to +23. The need is for the circuits of microcontrollers, chips , ic’s ,etc can be interfaced from this conversion. Then from the other end we can use this to connect to the laptop or pc. Then from this we can modify various memory ,rom, codes etc by using a suitable software in the laptop or pc.