SIM cards - functions and features. Difference between types of SIM cards. How to change SIM card size

SIM card (English: subscriber identification module) is a subscriber identification module used in mobile communications.

With the development of technology in the mobile industry and the growing requirements for cell phones, there is a need to create new formats of SIM cards for phones.

This is due to the fact that the hardware of today's phone is becoming more and more complex, and the size of modern smartphones is becoming smaller. Thus, manufacturers have to save as much space as possible when developing new phone models.

The picture clearly shows the differences between different types of SIM cards. the biggest - full size sim(86.60x53.98x0.76). Few people saw the “big SIM card”; such SIM cards appeared in 1991 and were used at the beginning of the development of cell phones. most people are used to the next largest SIM card mini-sim(25x15x0.76), such a card appeared in 1996 and is installed in almost all GSM phones. next in size is micro-sim(15x12x0.76), 2003, this standard was introduced and is used in smartphones 4, 4s, as well as all first generations of iPad. the smallest card - nano-sim(12.30x8.80x0.67), this standard was also introduced in October 2012 and is used in phones starting with smartphone 5 and iPad mini tablets.

Options for the next generation of SIM cards (5ff) are being developed, which will probably not be replaceable.

How to cut a SIM card for micro sim?

Having bought a new phone or tablet (for example, htc, smartphone or ipad), you may find that a standard SIM card does not fit it and in order to continue using your usual SIM card after purchasing a new device, you need to cut it off. The main chip remains in place, only the size of the plastic base is reduced. It’s not difficult to make a micro sim from a regular SIM card at home; you only need sharp nail scissors, a sharpened pencil, a ruler, sandpaper (or a nail file) and a little patience.

As mentioned above, a regular SIM card is a plastic rectangle with a chip with parameters of 25x15 mm. The dimensions of the micro SIM card must be 15x12 mm. You can cut a regular SIM card to the desired size as follows:

This method is also suitable if you need to cut microsim to nanosim.

If the SIM card after resizing is larger than necessary, this can always be corrected; if the size is significantly smaller, the SIM card will become impossible to use and you will have to change it to a new one.

The opposite situation is also possible - using a micro SIM card in devices with standard slots. To do this, you will need a special adapter for micro SIM cards, which can be purchased at any communication store. this way, your micro SIM card will become universal for most devices.

Do you want to use several SIM cards in your phone at once? Then buy yourself with cash on delivery.

In order to be able to make and receive calls from your smartphone or tablet, and use other services of cellular operators, you must have a SIM card. In fact, each SIM card is a miniature chip that contains all the information necessary for normal operation in the cellular network: subscriber identification number, etc.

Navigation

IMPORTANT: We can say that the Sim card is the interface between the subscriber and his mobile operator.

Just a few years ago there was one standard for SIM cards. Today there are several of them. And the main difference between SIM cards from each other is their size. The newer the standard of such a card, the smaller it is. Below we will talk about what sizes of SIM cards exist and how they can be changed if necessary.

Today, there are three main SIM card standards used in cellular communications: Mini, Micro and Nano.

Mini-SIM

This is the oldest format to date and consists of standard-sized SIM cards. Their dimensions are equal 25 × 15 mm. Such cards are used on most mobile phones. New smartphones practically do not support this size of SIM card, but if necessary, using improvised means, you can cut a card of the required size from an old SIM card.

Micro-SIM

As the name of this standard implies, the Micro format differs from Mini primarily in size ( 15 × 12 mm). For the first time, such a standard was used by Apple in its iPhone 4 smartphones. And the overwhelming number of new smartphones use exactly this SIM card format.

If you bought a smartphone that works with a SIM card of this format, then do not rush to your operator’s mobile phone store. In most cases, you can trim the card to the desired size at home. But more on that below.

Nano-SIM

Nano-SIM is the smallest size SIM card available today. As in the case of Micro-SIM, Apple started a “revolution” by developing this standard for its new iPhone and iPad models. But, some developers of devices on the Android operating system supported the company from Cupertino and also use Nano-Sim in their devices, saving space and reducing the size of gadgets.

Nano-SIM Dimensions 12 × 5 mm. If you look at such a SIM card, you will notice that this is a chip without the plastic that was previously used around it.

How to change SIM card size?

The easiest way to change the size of a SIM card is to replace it with your mobile operator. But, this can be done at home. You also need to know that in services, salons selling mobile phones, etc. You can order the card to be cut to the desired size.

Contact your telecom operator

If you don’t want to bother with the SIM card and cut it manually, then go to your operator’s office with your passport and order a SIM card replacement service. It's free and only takes 2-3 minutes. You will be given a card of the required size (or a multi-format card from which you can “squeeze out” the card of the required size yourself).

IMPORTANT: Your phone number, connected services and balance will remain the same as before replacing the card.

Modern SIM cards are multi-format. This means that by registering with a mobile operator, you will receive a card from which, without any improvised means, you can make one that you can use in your device.

In such a SIM card, the dimensions of the format you need are indicated using a dotted line. It is almost impossible to damage the chip when “squeezing out” the size you need.

Let's go to the workshop

If you don’t have the time or opportunity to get to your operator’s office, then go to any mobile phone store (or gadget repair shop) and order a SIM card cutting service.

Almost every such workshop has a special stapler device with which you can cut the card to the desired size in a few seconds. At the same time, the risk of damaging the chip is even less than when “squeezing out” the SIM card along the dotted lines.

Cut by hand according to the template

You can cut out the SIM card using regular scissors. It is best to cut according to a template. If you don’t have one, you can find such a template on the Internet and print it on a printer. Then cut out the template and attach it to the SIM card. Now carefully cut it along the contours of the template. If necessary, sand the edges with fine-grit sandpaper after cutting.

IMPORTANT: When applying a template to a SIM card, make sure that the chip on your card and the template match. If this is not done, the performance of the cropped card may suffer.

Insert into the device and use.

Instead of a conclusion

Hopefully this article will help you understand more about SIM card formats, as well as how to adapt your SIM card to the supported device size. If you are afraid of damaging your card, then order it to be replaced or cut to the required size from professionals. If you don’t have time, you can trim it yourself. The main thing is to do everything carefully and according to the template.

Video. How to make a Micro or Nano SIM card from a SIM card with your own hands

SIM card is a device that is a subscriber identification module. It is an integrated circuit designed to securely store an International Mobile Subscriber Identity (IMSI) number and its associated key, which are used to identify and authenticate subscribers to mobile telephony devices (such as mobile phones and computers). In addition, you can store contact information on many SIM cards.

SIM cards are always used on GSM phones; for CDMA devices they are only required for new LTE-compatible devices. They can also be used in satellite phones.

The SIM card is part of a universal feature (UICC), which is usually made of PVC with built-in contacts and semiconductors. A SIM card, the device of which is based on digital technology, can transfer data between different mobile devices.

SIM card contains:

unique (ICCID);
international mobile phone number (IMSI);
authentication and encryption;
temporary information about the local network;
a list of services to which the user has access;
The phone's SIM card device also has two passwords: a Personal Identification Number (PIN) for normal use and a Personal Unlock Key (PUK) for PIN unlocking.

History and market entry

The SIM format was originally defined by the European Telecommunications Standards Institute in specification number TS 11.11, which describes the physical and logical properties of a SIM card. With the development of UMTS, specification work was partially transferred to 3GPP.

The first SIM card was developed in 1991 by Munich smart card manufacturer Giesecke & Devrient, which sold the first 300 copies to Finnish wireless network operator Radiolinja.

Inactivation

In many pay-as-you-go contractual agreements, you are required to use prepayments periodically to avoid account expiration. This period depends on the network operators, but is usually defined as a period of three months. This is sometimes due to the SIM card becoming inactive on the network.

Registration

Most countries and operators require identification to activate the service, but there are some exceptions such as Hong Kong SAR.

How does a phone's SIM card work?

SIM cards have three operating voltages: 5 V, 3 V and 1.8 V. The operating voltage of most SIM cards launched before 1998 was 5 V. Subsequently created cards are compatible with 3 V and 5 V. Modern copies support voltage 5 V, 3 V and 1.8 V.

Data

SIM cards store network information used to authenticate and identify subscribers on the network. The most important ones are ICCID, IMSI, Authentication Key (Ki), Local Area Identifier (LAI) and Operator Number.

A SIM card whose device is based on circuits also stores other operator-specific data such as the Short Message Service Center number (SMS ServiceServiceName), Service Provider Name (SPN), Service Numbers (SDN), Advanceofcharge parameters and applications with value added (VAS).

SIM cards can be supplied in varying data sizes from 8 to at least 256 KB. They all allow you to store a maximum of 250 contacts, but while the 32KB version has room for 33 mobile network codes (MNCs) or "network identifiers", the 64KB variety has room for 80 MNCs. This metric is used by network operators to store information about preferred networks and is mainly used when the SIM is not on its home network, but roaming. What does this phone SIM card device mean?

The operator who issued the SIM can use this to connect the phone to their preferred network to take advantage of the best commercial deal for the original network company. This does not mean that a phone containing this SIM can connect to a maximum of 33 or 80 networks, only that the SIM card issuer can only specify up to that many preferred networks. If the SIM is outside of these preferred networks, it will use the first or best available one.

ICCID

Each SIM card is identified internationally by an integrated circuit identifier (ICCID). ICCIDs are stored on SIM cards and are also engraved or printed on the case during the personalization process.

The ICCID is defined by ITU-T Recommendation E.118 as the Primary Number. Its layout is based on ISO/IEC 7812. According to E.118, the number can be up to 22 digits, including one check digit calculated using the Luhn algorithm. However, GSM Phase 1 defined the ICCID length as 10 octets (20 digits) with a specific operator structure.

International Mobile Subscriber Identity (IMSI)

SIM cards are identified within individual operator networks using a unique International Mobile Subscriber Identity (IMSI). Operators connect to mobile phone calls and exchange their SIM cards in the market using their IMSIs. Their format is as follows.

The first three digits represent the Mobile Country Code (MCC).

The next two or three digits represent the mobile network code (MNC). Three-digit MNC codes are permitted by E.212 but are primarily used in the United States and Canada.

The following digits represent the Mobile Subscriber Identification Number (MSIN). Typically this is 10 digits, but the value will be less in the case of a three-digit MNC or if national regulations specify that the total length of the IMSI must be less than 15 digits. All these numbers differ from country to country, so there may be differences in how the SIM card is designed. The circuit is standard and factory-made, the difference is only observed in the recorded information.

Authentication Key (Ki)

Kni is a 128-bit value used to authenticate SIM cards on the GSM mobile network (for the USIM network you still need Ki, but different parameters are required). Each SIM card stores a unique Ki assigned to it by the operator during the personalization process. This setting is also stored in a database (called an authentication center, or AuC) on the carrier's network.

How is a SIM card designed taking into account the above? It is designed to prevent Ki from being obtained through the smart card interface. Instead, the SIM card provides a "Run GSM Algorithm" feature that allows the phone to transfer data to the SIM card, which must be signed with Ki. This in theory makes the use of a SIM card mandatory if Ki cannot be removed from the SIM card or the operator wishes to disclose this option. In practice, the GSM cryptographic algorithm for calculating SRES_2 (see step 4 below) from Ki has certain vulnerabilities that could allow this value to be extracted from the SIM card and create a duplicate SIM card.

Authentication process

When the mobile equipment starts up, it obtains the International Mobile Subscriber Identity (IMSI) from the SIM card and passes it to the mobile operator, requesting access and authentication. Mobile equipment may transmit a PIN code to the SIM card before it reveals this information.

Location Area Identification

The SIM stores network status information, which is received from the Location Area Identifier (LAI). Operator networks are divided into location areas, each of which has a unique LAI number. When the device changes location, it stores the new LAI on the SIM card and sends it back to the carrier network with the new location. If the device is running cyclically, it will retrieve data from the SIM card and search for the previous LAI. Some listening devices with a SIM card also work on this feature.

SMS messages and contacts

Most SIM cards will by default store a number of SMS messages and phonebook contacts. Contacts are stored in simple name and number pairs: entries containing multiple phone numbers and additional phone numbers are typically not stored there. Such conditions are provided by the SIM card device. Contacts can be saved to a very limited extent. For example, when a user tries to copy such entries to a SIM card, the phone's software splits them into multiple entries, discarding any information that is not a phone number.

The number of saved contacts and messages depends on the SIM card. Early models will only store five messages and 20 contacts, while modern SIM cards can typically store more than 250 items.

SIM card: device and formats

Over the years, SIM cards have become smaller, and their functionality does not depend on the format. The full-size SIM card was followed by mini-SIM, micro-SIM and nano-SIM. Today they even come built into devices.

Full size SIM card

The full-size SIM card (or 1FF, 1st form factor) became the first form factor. It is the size of a credit card (85.60 x 53.98 x 0.76 mm). Later, smaller SIM cards were often sold built into a full-size card from which they could be ejected.

Mini-SIM

A mini-SIM (or 2FF) card has the same contact arrangement as a full-size SIM card and usually comes in a full-size adapter with connectors attached to it. This scheme allows it to be used both in a device that requires a full-size card, and in a device that requires a mini-SIM card (after breaking the connecting elements). Since the full-size SIM card is no longer used, some vendors refer to this form factor as a standard or regular SIM card.

Micro-SIM

A micro-SIM (or 3FF) card has a similar thickness and pin layout, but is distinguished by a reduced length and width.

The micro-SIM format was introduced by the European Telecommunications Standards Institute (ETSI) for installation in devices too small for a mini-SIM card. The form factor was mentioned in the 3GPP SMG9 UMTS working group, which is the standards-setting body for GSM SIM cards, in December 1998, and subsequently agreed upon in late 2003.

Micro-SIM was developed for the main problem was the contact area of the chip. Maintaining the same contact area allows the micro SIM to be compatible with previous, larger SIM card readers through the use of plastic cutouts. The device has also been designed to operate at the same speed (5 MHz) as the previous version. The identical pin sizes and positions have led to numerous tutorials and YouTube videos detailing how to cut a mini-SIM card to micro-SIM size. However, such actions at home sometimes lead to the fact that the SIM card does not correspond to the device or becomes completely unusable.

Nano-SIM

The nano-SIM (or 4FF) card was introduced on October 11, 2012, when mobile service providers in various countries began shipping it for phones that supported the format. The Nano-SIM measures 12.3 x 8.8 x 0.67 mm and reduces the previous format to just the contact area while maintaining existing features. A small rim of insulating material is left around the contact area to prevent short circuits. The Nano-SIM is 0.67mm thick compared to its predecessors' 0.76mm. 4FF cards can be placed in adapters for use with devices designed for 2FF or 3FF SIM cards and made thinner to do so, but many phone companies do not recommend this.

The iPhone 5, released in September 2012, was the first device to use activated nano SIM cards, followed by other phones.

The upcoming new generation of SIM cards is called e-SIM or eSIM (embeddedSIM), which is a non-replaceable built-in chip in a SON-8 package - soldered directly onto the circuit board. It will have M2M and remote SIM capabilities.

What could be simpler than a regular SIM card installed in our smartphone? Today, almost every person already has at least one copy of this product. And many people might have dozens of such plastic cards lying around in their desks. It would seem that in the era of frameless smartphones, wireless charging, sending Teslas into space, nothing could be simpler than a small SIM card, but in reality everything is far from so simple.

The principle of SIM cards is undeservedly considered extremely simple, although, by and large, this is a real computer, presented in such a compact form factor. Today I will try to briefly go over the modules and types of SIM cards, and perhaps you will be seriously interested in this topic.

What is a SIM card

The chip, so familiar to any person today, is a subscriber identification module (this is how the abbreviation SIM is literally translated). The history of the first “SIM cards” in the form in which we are accustomed to seeing them begins in 1991, it was then that full-size cards first appeared.

Subscriber Identification Module - subscriber identification module.

Despite its size and, as it seems to the average person, primitiveness, this card stores a lot of information. This includes the international subscriber identifier IMSI, and the phone number, tariff plan, connected services, and other information installed on the card.

SIM card device

Due to the fact that the main purpose of calling cards is to store subscriber data, many people mistakenly believe that a SIM card is a more primitive analogue of a flash drive. This is not strange, because even in its shape the SIM card is quite similar to modern microSD cards. In reality, any SIM card is a meager analogue of a computer. Each card includes:

Microprocessor;
Permanent memory, which is used to store information and the OS (yes, SIM cards have an operating system);
RAM.

Of course, in the context of today's size of content and equipment installed in smartphones, laptops and desktop PCs, the amount of built-in and RAM memory on SIM cards seems insignificant, but they are enough to store operating and file systems, subscriber information, and even a user phone book . What, if all this, confirms that any SIM card is a real micro-computer?

Current SIM card formats

In addition to the design of telephone cards, I also wanted to focus your attention on the existing formats, or standards, of SIM cards used today. You can select 5 of them:

Mini-SIM is a standard of cards that were installed in every phone not so long ago, until they were replaced by smartphones with smaller slots. Such a card has a size of 25 by 15 by 0.76 millimeters, and today is used only in push-button and outdated phone models;
Micro-SIM is a card that replaced the Mini version and has more compact dimensions of width and length (15 by 12 mm) while maintaining the same thickness of 0.76 mm. This card has become popular with the spread of smartphones. However, today its popularity is gradually “fading away”;
Nano-SIM is the most common SIM card format today, having more compact dimensions in width, length, and thickness (12.3 by 8.8 by 0.67 mm). Its size is slightly larger than the golden chip itself, which could always be seen on SIM cards;
eSIM is another card option, the difference between which lies not in size, but in areas of application. The prefix “e” means “Embedded”, or “Built-in”, “Pre-installed”. Such cards are installed by default in contract models of gadgets. And, if such a need arises, removing and replacing them becomes quite problematic. However, such cards cannot be called popular on the territory of the Russian Federation;
Multi-SIM is the latest version of cards, representing a “matryoshka”, in which the layers of the card stencil are already marked by default. Having purchased such a SIM, with a simple finger press, you can select the required card format suitable for the slot in your mobile phone.

This was a brief educational program regarding the history, formats and design of modern (and not so modern) SIM cards. I hope this information was interesting and you learned something new.

Once upon a time, more than 20 years ago, which by the standards of the modern IT industry can even be considered untrue, mobile phones used special numbers recorded in them at the factory to identify themselves in the cellular provider network. However, this approach was not very convenient for both users and manufacturers. They were interested in "separating" the subscriber ID from the hardware. This is how the idea of using additional individual cards with built-in microcircuits arose. This approach is used today in networks of various standards - GSM, CDMA, UMTS, LTE, but we will talk mainly about the most widespread option - GSM/3G.

The telephone device, as a physical device, has an IMEI (International Mobile Equipment Identity) number, which can be considered unique on a global scale. It participates in the transaction logs of the cellular operator and, in principle, can be used to block access to the network, search for stolen phones and other similar actions. In some countries, it is illegal to falsify or change this number. The IMEI number can usually be found on a sticker under the battery and on the box. From a technical point of view, it is written electronically in one of the microcircuits and, of course, can also be read programmatically. If the telephone has the ability to install several SIM cards, then there are also several IMEI numbers. This number is available not only for phones, but also for modems, tablets and other devices designed to work in mobile networks. Formally, manufacturers could get by with just this number and not use traditional serial numbers for their products, but today this “separate” approach is more convenient for them.

A similar SIM card number is called ICCID (Integrated Circuit Card Identifier). It is often engraved on the cards themselves. It is similar to the serial number of the device - the only difference is that it is unique and cannot be repeated on any other card in the world. Although if you add the manufacturer and model name to the serial number of the phone, then this combination will also be unique.

Direct identification of the subscriber in the cellular network takes place using the IMSI (International Mobile Subscriber Identity) number, which is recorded in the SIM card. This number determines the ownership of the card by the operator and allows you to link the card user with his account with the provider, including the phone number, permitted services, and so on. The card also stores other unique information, the description of which is beyond the scope of this article.

A few words should be said about card protection. The first milestone is a four-digit PIN code. If you don't know it, you won't be able to use the card to access a cellular network or read your address book. The user can change or cancel this code (it is usually disabled on newly purchased cards). If the PIN code was entered incorrectly several times, to unlock it you need to use the PUK code, also provided by the operator along with the SIM card. Even less commonly used are PIN2 and PUK2 codes, which allow the user to limit the list of allowed subscribers for outgoing calls.

But even if you know all these codes, you won’t be able to copy the card using everyday methods. There is another special code written inside it, known to the operator, which is used in the identification algorithm. This process is designed in such a way that the pure code is not transferred from the card to the phone. Instead, the device sends a task to the SIM card processor to encrypt the key, and transmits the response to the operator. The latter compares the result with that received in its data center, and if they match, the subscriber gains access to the network.

One of the popular options for “full-size” smart cards today

Technically, a SIM card is one of the variants of smart cards - microcomputers with their own processor and memory that communicate with the outside world through an interface of several electrical contacts. Smart cards are found today in the banking industry, used for access control and in various payment systems. Usually the card has several kilobytes of permanent memory, a couple of kilobytes of RAM and some flash. In the case of phones, the latter was previously used to store a notebook, but the limit on the number of entries (250) and support for only two fields (name and phone) has practically deprived it of this role today.

Electronic filling takes up very little space

Formally, the card has eight contacts for connecting to a reader (if you try really hard, you can try to count more). However, in reality only six are used. And given modern progress in microelectronics, the filling takes up literally a few square millimeters.

But if we talk about external dimensions, then it all started with a credit card format - 85.6 × 53.98 × 0.76 mm. This format of smart cards is still used today, but it stopped satisfying the wishes of cell phone manufacturers a very long time ago. Much more practical is the Mini-SIM version, which measures 25x15 mm with a beveled corner (to determine the required orientation of the card in the slot). The thickness did not change. It is this format that is the most widespread today and is found in most cell phones.

Mini-SIM and Micro-SIM cards use much less plastic

It is clear that such a reduction did not bring any losses in terms of functionality. But you need to understand that Mini-SIM is good specifically for placement in a telephone body. Using a card of this size, for example, for payphones, is obviously inconvenient.

After the massive transition to the Mini-SIM format, for a very long time it remained practically the only option for use in the field of mobile communications. Even successes in reducing the external dimensions of telephone sets did not require further reduction of the subscriber card. But still, he was not allowed to gain a foothold for centuries.

Special frames can be used to install Micro-SIM (sometimes Mini-SIM)

One of the most active market players in its new smartphone model two and a half years ago implemented work with the Micro-SIM format, the dimensions of the cards are 15x12 mm (the thickness has not changed again). For cards of this format, almost the entire front surface was occupied by contact pads. But there were no technical difficulties for him to place the chip, especially with the development of chip manufacturing technologies. Note that, from a consumer device design perspective, the market did not require this step. So, rather, the company played in the field of marketing, once again repeating “we are not like everyone else.”

Electronic “filling” takes up very little space even in Mini- and Micro-SIM

Interestingly, this year the same manufacturer played this card again. The latest model of their smartphone works exclusively with Nano-SIM, in which the thickness has already been reduced - 12.3 × 8.8 × 0.67 mm. Eight standard contacts no longer fit into this format, so only six truly working ones remain. No technical functions of the card were affected this time either, but the size of the new phone was not as reduced as one might think (and some even increased).

Almost the entire front surface of Nano-SIM is occupied by contact pads

A very reasonable question arises: how does this miniaturization story affect consumers? If we talk about those who buy a new phone with a contract and a new card, they usually don’t care what version of the SIM card is installed in it. And if a person basically has only one phone or he doesn’t plan to rearrange cards, then it’s not even “usually”, but “absolutely”.

To install Micro-SIM in the Mini-SIM bay, you can use adapters

But for those users who are accustomed to using several devices and/or SIM cards, the situation is less pleasant. In the case of a Mini/Micro pair, you can try to make do with so-called adapters/adapters (of course, after replacing all Mini format cards with Micro format cards). There are no advantages to this story, only disadvantages - you need to carry additional parts with you, and in addition, the adapter can damage the connector contacts during replacement (or the assembly may even get stuck in the slot).

As for changing cards, the official way is to visit your operator’s salon, write an application, wait and all that. In addition, if you suddenly have some entries on the card, you will need to take care of saving them. A more affordable option in terms of time spent is to contact numerous workshops, where your card will be cut with a special tool in a couple of seconds (by the way, large salons and even the operators themselves do this). If you really don’t want to go anywhere, then a sharp knife and a strong hand can also successfully solve the problem. For the first time, a printout from the Internet with a “cutting” diagram may be useful (see, for example,).

With Nano-SIM the situation is more complicated, since both the linear dimensions and thickness of the card are smaller. The methods remain the same. But at present the first of them should be recognized as the most correct. However, given the prevalence and cost of the device, for which you may need a Nano-SIM, this should not be a problem.