Your individual imsi identifier which. What do the numbers on the SIM card mean? IMSI Authentication Service¶
Please provide clarification. Where does the bank get information about changing the IMSI SIM number user cards? This information is confidential and is available only to the telecom operator. The telecom operator issues a unique IMSI SIM card number to third parties only upon an official request from authorized bodies (for example, police, court). The fact is that you receive SMS messages about transactions (including messages with one-time passwords) from the bank to a phone with a SIM card, the number of which (the so-called IMSI) is known to the bank. A person using a different SIM card with the same phone number but a different IMSI number will not be able to receive these messages. As a rule, re-registration of an IMSI number is carried out in the following cases:
- If you have changed your SIM card from your mobile operator to a new one.
- If you used the “Spare SIM card” service of your mobile operator and activated the spare SIM card.
In GSM/GPRS/UMTS networks, certain identifiers exist and are used to describe subscribers, network equipment, and location. Some of them are temporary and are used for privacy/security (for example, IMSI is permanent, TMSI is temporary). Some identifiers are common to CS (Circuit Switched) and PS (Packet Switched) MS (Mobile Station) operating modes, some are not. Here are just the main ones:
- ( Mobile Station Integrated Services Digital Number) – the subscriber's telephone number associated with the SIM card. Used in the CS domain. This is the number we dial when we want to make a call or send an SMS. MSISDN together with IMSI make up a pair of identifiers that uniquely identify the subscriber. MSISDN is used to route calls, while IMSI identifies a specific SIM card. For example, when changing a number, it is not necessary to change the SIM card; it is enough to change the MSISDN - IMSI combination in the HLR (Home Location Register).
CC (Country Code) – The code of the country in which the subscriber connected to the network (where the SIM was issued).
NDC (Network Destination Code) - National code of destination. For GSM networks it is assigned for each operator. For large operators, more than one NDC is allocated. It is the CC and NDC fields that allow you to obtain information about routing to the HLR and the call. The PCS1900 system uses the field instead of NDC NPA – Numbring Plan Area.
SN (Subscriber Number)- Subscriber number.
The specific lengths of the component parts are regulated by international and local legislation, for example: Russia: CC=1 digit (7), NDC=3 digits (for example, 910), SN=7 digits (1234567), total - 11 digits (final example: 7- 910-1234567).
You can check which telecom operator this or that number belongs to, for example, on the MTT website.
- IMSI(International Mobile Subscriber Identity). This identifier is used to uniquely identify each subscriber, or more precisely, his SIM card. IMSI does not depend on the telephone set that the subscriber uses. Stored in AuC (Authentication Centre) – the Authentication Center of the subscriber’s home network and on the subscriber’s SIM card in an elementary file (EF) with the identifier 6F07. The IMSI storage format on SIM is adopted by ETSI in the GSM 11.11 specification.
MCC – Mobile Country Code. TO od of the country in which the operator is located. Describes the “home” country of the mobile subscriber. For example, in Russia MCC=250.
MNC – Mobile Network Code. Mobile network code. Uniquely describes the subscriber's network. MNC of our operators. MNC = 01 MTS, MNC = 02 Megafon, MNC = 99 Beeline, MNC = 20 TELE2 Russia.
MSIN -Mobile Station Identification Number. Defines the SIM number. Uniquely describes a SIM within a single network. The first 3 digits describe the subscriber's HLR.
The IMSI identifies the subscriber in the HLR. When a subscriber registers in MSC or SGSN, the subscriber’s device transmits IMSI, which is used to identify him in the HLR (allow/deny access to the network, information about connected services, etc.). To avoid interception, this number is sent over the network as infrequently as possible - when possible, the VLR and SGSN may use a randomly generated TMSI instead. In this case, the VLR and SGSN contain a correspondence between the IMSI and TMSI for each MS. TMSI is used for CS services, and P-TMSI is used for PS services.
- TMSI(Temporary Mobile Suscriber Identity) /P-TMSI(Packet Temporary Mobile Suscriber Identity). E then two temporary identifiers are used for subscriber confidentiality. They are assigned in encrypted form after successful authentication, for CS services TMSI, for PS, respectively, P-TMSI. In any case, whether a TMSI is assigned or not, the MS will respond to its IMSI. TMSI length is 32 bits (4 octets). If all 32 bits are 1, then the SIM card considers that TMSI/P-TMSI are not used. TMSI only matters within one Location Area. TMSI/P-TMSI are used for paging (paging occurs within the same LAC/RAC). In case of simultaneous existence of CS and PS services, certain rules are used in assigning TMSI/P-TMSI. If the 2 most significant bits are 00, 01, 10, they are used by the VLR for TMSI. The value 11 is used by the SGSN to assign P-TMSI.
- IMEI(International Mobile Equipment Identity). International mobile equipment identifier. IMEI is installed on phones during manufacturing at the factory. It serves to identify the device on the network. IMEI is used only to identify the device, and has no permanent relationship with the subscriber. You can view it by dialing *#06#. In essence, IMEI is an analogue of a MAC address. Operators have the ability to track stolen and other gray devices by IMEI and block access to the network; EIR (Equipment Identity Register) is used for this, but is not yet used in Russia.
TAC – Type Approval Code. Assigned to series of mobile phones after testing. Before 2002, the TAC consisted of only 6 digits, the remaining 2 digits being the final assembly code (FAC). From 2003 to 2004 there was a transition period during which all FAC codes were equal to the digits 00. In 2004, FAC ceased to exist and TAC was expanded to 8 digits.
FAC – Final Assembly Code. This is the code for the final assembled product. Added to identify the manufacturer.
SNR – Serial Number. Serial number
The MEID (Mobile Equipment Identifier) operating on CDMA networks uses the same basic format as the IMEI. You can find out the phone model by IMEI, for example.
IMSI (stands for International Mobile Subscriber Identity) is an individual number assigned to each subscriber. When connecting to a mobile operator, the IMSI is read by the system, after which it is identified.
Using IMSI allows you to secure the transmission of passwords, registration codes and other data of this kind via SMS. You can be sure that the message will reach the intended recipient.
HLR request and IMSI - example in mailings
The combined use of IMSI and HLR requests allows you to:
- check the client's SIM card when making payment transactions. If fraudsters try to copy the number using a duplicate SIM card, a confirmation code will not be sent to them
- check the SIM card when confirming other actions via SMS. Such actions include: sending an authorization code, information about account states, confirmation of login, receipt/debit of funds
- compile lists of clients to call. Clients may be in different time zones, so it is important to choose a favorable time to call. IMSI and HLR requests also make it possible to find out whether a subscriber is active or inactive. Inactive numbers are not called
- get DEF code. The numbers of some clients may be saved without operator codes, which will cause difficulties in sending SMS messages. Obtaining the DEF code of a phone number allows you to bypass all these difficulties
Test number verification:
Test the accuracy of the number verification service. Just enter any number in the form below and receive the following information: the operator currently servicing the number, whether the number was transferred (and if so, who served it previously), the name of the legal entity. person, brand, and region of the operator that issued the SIM card for this number
Surely many have heard that the SIM card stores some kind of subscriber identifier called IMSI. They know that for each subscriber it is unique. However, it is impossible to find it written down somewhere.
IMSI is an individual number for each subscriber, by which the system recognizes a mobile communications user using the GSM or UMTS standards. At the time of registration on the network, the subscriber’s device transmits the IMSI identifier, with the help of which identification occurs. In order to eliminate the possibility of unauthorized interception, this number is sent over the network as rarely as possible. In all cases where such an opportunity exists, TMSI is sent instead, a code that was randomly generated using a specific algorithm. TMSI is an identifier of a specific mobile station, used as a temporary one during the registration process in the network, when setting up a call, and the like. Its assignment is possible only after successful completion of authentication using IMSI.
The identifier in the GSM system is contained in an elementary file on the SIM card; this file has the identifier 6F07. The format in which the IMSI is stored on the SIM card is described by the ETSI standard provided for by the GSM 11.11 specification. In addition, IMSI is used by any mobile network that is connected to other networks, such as CDMA or EVDO, identical to GSM networks. This number is associated directly with the phone, but may have a connection with the R-UIM card, which functions as a SIM card for CDMA systems.
Typically the IMSI is 15 digits long, but can sometimes be slightly shorter. For example, a standard 15-digit IMSI: 250-07-XXXXXXXXXX. The first three digits (250) determine the country (Russia). Next (07) the mobile network (CMAPTC) is encrypted. The mobile network code uses two or three digits - two for the European standard, and three for the North American standard. All remaining digits are the user identification number.
E.212ITU is a numbering standard that IMSI conforms to.
Every cellular user has noticed that the SIM card does not always indicate the phone number, but there are other digital codes. Also, when replacing a SIM card or operator with their number, the subscriber receives a new card on which the main number is not indicated, and the remaining designations differ from those on the old card.
Today we will tell you what kind of identification numbers are written on SIM cards: what they are for, what they mean, and how they differ on MTS, Beeline, and MegaFon.
What is indicated on the SIM card
When receiving a new SIM card, the subscriber is issued a card by the mobile operator, the size of which is identical to a bank card. Usually we just break out the chip of the required size, install it in the phone, and start using the connection.
Not all users attach importance to the so-called plastic base that frames the SIM card itself, and often throw it away. However, it is the plastic base that contains important information, some of which, of course, is not useful for the subscriber to use and is of a purely technical nature. However, the SIM card itself also contains useful information.
In recent years, SIM cards have evolved significantly, and first of all, their size has changed. Most modern gadgets use the nano format. However, even on such a small piece of plastic with a built-in chip, the operators indicate not only the operator’s logo, but also the unique serial number of the SIM card, the numbers of which are different for the sim of Beeline, MegaFon, or another operator.
First, let's talk about the information indicated on the plastic base of the SIM card and how it can be useful. Surely you have noticed that operators began to issue cards divided into two parts. The first contains a chip, and the second contains basic information about the operator. Operators recommend separating the second part of the card and saving it.
What is so useful indicated on it? Here the subscriber can receive basic information about the operator, including the Internet portal and contact center number. If a subscriber is just starting to use the operator’s services, then such information will be useful - how to get advice, quickly check the balance, or the balance of package services.
Also on this part of the card is the number itself, which can be placed in the form of a sticker, and personal SIM codes. Depending on the operator, there may be two or four.
The first pair of codes must be present on SIM cards of any operator - these are PIN and PUK. In recent years, when activating a new card, the PIN is not activated by default, but you can enable its request. This will avoid unauthorized access to the number if the SIM card falls into the wrong hands.
Many will ask: why an additional code if the SIM card is protected on the device with a password, or even access by fingerprint? To gain access to a SIM card, just install it in another phone, and it will work without a pin. If you activate the PIN request, access will be impossible without entering it.
Today, operators release SIM cards with an initial pin of four zeros or ones, but the pack is always unique. The fact is that the pin can be changed, which will protect your SIM card. The PUK cannot be changed, and if it is entered incorrectly ten times, the card is completely blocked. To restore access, you do not need to change the card itself, but simply request a PUK code from the operator.
The second pair of codes is not specified by all operators. PIN2 and PUK2 are used to work with additional operator services. Thus, activation of individual services through the device menu is available only when entering PIN2, and PUK2 is used like the first if you have forgotten your PIN code.
What does the serial number mean?
The serial number is used not only in the production of SIM cards, but also in most other technical products. Thus, any mobile gadget can be identified not only by its imey code, but also by its serial number. It encrypts information about the manufacturer, and even the release date.
On SIM cards, the serial number is designated ICCID. What do the numbers in this ICC SIM mean, and why is it indicated on the SIM card itself, where is the chip located, and how do they differ on MTS, MegaFon, or Beeline?
This code has a uniform standard throughout the world, and it can be used to not only determine the country, but also the cellular operator. Regardless of the company that issued the SIM card, as well as the country, the ICC always begins with the number 89. Next, the country code is indicated, so on Russian SIM cards it is always a seven. Depending on the country, this part of the code can contain from one to three digits.
After that, the mobile operator ID is indicated, consisting of two to four digits. However, there is a peculiarity that, together with the country code, it forms a five-digit number. Accordingly, all Russian mobile communication providers have codes consisting of four digits.
Next comes eleven digits, which can be considered the identifier of the SIM card itself. This sequence is determined by operators according to their own rules, which do not have a common standard. Using this code, the physical SIM card is linked to the operator’s software ID. The last number or letter is the check number.
The operator writes another code into the SIM card itself - IMSI, which serves as an identifier for each specific subscriber. It contains information about the country, mobile operator, and subscriber number. The code consists of fifteen digits.
It is thanks to IMSI that a cell number is linked to a plastic card with a chip used to receive cellular services. So, if you contact the operator to replace or get a new SIM card, then the store will take a free SIM card that is not tied to a specific number. The operator's employee assigns a subscriber number identifier to it, and after processing the information in the system, the IMSI is linked to the received card.
