What does a real SIM number look like inside? Location Area Identification

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At the end of May, the European Telecommunications Standardization Institute (ETSI) will vote on a new SIM card standard, the so-called nano-SIM, which will be 20-35% smaller than the current micro-SIM used in the iPhone, Nokia Lumia and other devices. To answer the question, why else should they be reduced, let’s go a little deeper into history.

For any device to operate on any provider network, some kind of identifier is required. In the era of the emergence of mobile communications, this identifier was a unique number that was assigned at the manufacturer, the so-called ESN (Electronic Serial Number). Switching from one operator to another was quite difficult, and sometimes even impossible without purchasing a new telephone. When purchasing a new device, it was necessary to come with it to the operator’s office to register it. This was extremely inconvenient, especially as the number of subscribers grew. Over time, mobile communications became available to almost everyone, and the number of devices began to grow continuously.

When developing the GSM standard, engineers placed the subscriber identifier into a separate module, which they called SIM (Subscriber Identity Module). Essentially, a SIM card is a microcomputer that verifies the legitimacy of the equipment and registers the terminal on the network.

Let me remind you that three types of SIM cards are currently standardized

SIM card is the size of a credit card (86*54mm). Appeared at the stage of formation of mobile communications of the GSM standard. Used in the then popular Motorola StarTAC series phones.
Mini-SIM is a classic small SIM card measuring 25*15mm. Ubiquitous in the vast majority of mobile devices.
Micro-SIM - a type of card popularized by Apple (15*12mm)

In the days of bricks, the size of SIM cards was of little importance, because... the equipment itself was quite large. External antennas, large batteries. For example, back in 1992, the first “handheld” GSM phone, Nokia 1011, measured 195 x 60 x 45 mm and weighed 475 g. Times changed, technological evolution moved forward, and the size of phones decreased. There was a need to reduce device components without compromising functionality. That's when it became necessary to reduce the size of SIM cards. All manufacturers began to switch to mini-SIM, the size of which was more than 12 times smaller than a standard SIM card. The emergence of mini-SIM was largely due to the race for phone sizes. Let's remember such phones as Panasonic GD55 or Motorola T191. These phones were so small that even the female half often experienced inconvenience in using them.

Now they are going to reduce the size of SIM cards again. There are four contenders for standardization. These are Nokia, Motorola, RIM (BlackBerry brand) and Apple. I'll tell you a little more about the SIM cards themselves.

Apple proposes to standardize a 12*9 mm SIM card, which will be held in devices using a special tray (which is already familiar to users of Apple gadgets), for which the company has received a patent. But Apple promised that if its decision was accepted, the company would license all patents needed for the standard for free.

This decision was strongly opposed by the Motorola-Nokia-RIM alliance, which proposed their own version of SIM cards, which are something similar to micro-SD cards and are held in the device in exactly the same way. The sizes of SIM cards offered by companies vary slightly. Nokia offers a SIM card size of 10*8mm, while RIM insists on a size of 11*9mm. Nokia, which has said it will not license its patents that would be necessary if the European Institute chooses Apple's solution as the standard, is leading a particularly fierce fight for the standard.

The selection of the standard will be carried out by voting by ETSI members. At the moment, 759 organizations from 60 European countries are members of the institute. And there is another scandal associated with voting. RIM accused Apple of trying to influence the outcome of the vote by registering its employees as representatives of other companies that are members of ETSI. In addition, Apple is now registering subsidiaries in European countries that are also members of the institute. Currently there are 6 companies registered in the UK, France, Germany, Switzerland, Portugal and Italy, while Nokia has 2 companies registered, Motorola has 3, and RIM is not represented at all. According to rumors, Apple will also be supported by telecom operators, but this is just a rumor. According to preliminary data, the vote should take place at the end of May, but there is no certainty that it will take place. Most likely, it will be postponed again and give time to the companies to come to an agreement among themselves.

The main question that may concern us, ordinary consumers, is what does changing the size of SIM cards give us? It is quite difficult to find positive as well as negative sides. With SIM cards getting smaller, phone sizes are unlikely to become smaller than they are now. Indirectly, this proves that no one except Apple was in a hurry to change mini-SIM cards to micro-SIM, although this standard was adopted long before Apple appeared as a player in the mobile phone market. And no one will make phones smaller - on the contrary, the trend of increasing screen sizes, as well as phone sizes, cannot be ignored.

Some might say that this will free up space in the devices for other components. But the freed-up volume is so small that it can hardly be used effectively. Also, changing the standard is unlikely to affect the final cost of the device. The only thing that can cause us inconvenience is visiting the operator’s office to replace the SIM card when purchasing a new device, but this is done only once. And you are also unlikely to experience any inconvenience from replacing SIM cards. Remember the last time you changed your SIM card.

Why is Apple trying to change the standard? This is understandable. They have already tested this technology, only the size of SIM cards will change. Perhaps in the future they will still license their technology with royalties. And there is no such thing as extra money. Why does the rest of the alliance need this? It seems to me that this is just to protect yourself from a possible monopoly by Apple and, of course, to make yourself known. As you can see, the “apple company” is opposed by players whose market performance has greatly declined in recent years. Sales volume is steadily decreasing, revenue and profits are falling. My statement indirectly proves the fact that such “giants” as Samsung, HTC and Asus do not speak out on this topic at all.

In conclusion, I want to say that whatever the result of the vote, there will be no shocks in the market, and this will affect you and me to a lesser extent. And even more so, do not forget that in extreme cases, all sorts of adapters will appear, with the help of which you can easily insert SIM cards into one or another device.

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. Making a micro sim from a regular SIM card at home is not difficult; 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.

No mobile device can operate on a carrier's network without a small chip commonly called a SIM card. This is a small chip surrounded by plastic. It contains all the necessary data for the network, and also allows you to save some user information - for example, a list of telephone numbers.

The SIM card is an intermediate link between the subscriber and the telecom operator

There are several types of SIM cards, differing in size. Moreover, the newer the standard, the smaller the card. The latest models increasingly use smaller SIM cards, so when buying a new phone, the issue of adapting the SIM card becomes relevant. In this article, we propose to familiarize yourself with the standards of SIM cards, understand what the difference is between them and how to reduce them for use in a new device.

Types of SIM cards

There are three main formats: mini, micro and nano. What are they?

Mini-SIM

Standard card format. Used in most modern phones. In everyday life, the name without the prefix “mini” is popular. The dimensions of this card are 25×15 mm. It does not need to be adapted, even if it is more than one year old. Just insert and use.

Micro-SIM

Compared to the previous type, micro-SIM has smaller dimensions - 15x12 millimeters. It was first used in the iPhone 4. Recently, this format has been increasingly supported. When buying a new phone, it’s easy to cut it off from a regular SIM card.

Nano-SIM

The latest, smallest SIM card used in the latest iPhones, iPads, and flagship Android models. The nano-SIM looks like a chip without any plastic around it. The card dimensions are small - 12x5 mm, so it is more difficult to adapt from larger formats.

How to change SIM card size

There are several options for changing the size of a SIM card: order a new one from your operator, contact a telephone repair shop, or cut a regular card yourself. In the latter case, there is a risk of damaging the card due to inexperience, and then responsibility for its damage will fall on you.

Contact your telecom operator

The simplest and surest way. You just need to come to the communication store with your phone and passport and order a SIM card replacement service. You will receive a new card of a suitable format, while your phone number, balance and connected services will be saved.

Recently, operators have been offering subscribers multi-format SIM cards that are suitable for all types of phones. The outer shell is a mini-SIM, from it you can use a nano-SIM along the indicated dotted line. You risk nothing and use communication services without any problems.

This service is completely free. In some cases, you need to pay a small amount, which will remain in your account. This option is offered by the operator Tele2.

Let's go to the workshop

If for some reason you cannot contact a communication shop or do not want to wait for a new card to be sent, then you can cut it at any workshop. This will be done using a device similar to a stationery stapler, into which a SIM card is inserted, and with one click the excess ends are cut off. This service is inexpensive, and in some workshops it is completely free.

Cut by hand according to the template

If the previous two methods are not available to you, try doing it yourself. To do this, you will need scissors, double-sided tape, a ruler, a pencil or felt-tip pen and the SIM card itself. You don’t have to calculate anything, just use a template popular on the World Wide Web. Download it from the link and print it at 100% scale on an A4 sheet. It can be used to make micro and nano-SIM.

Using double-sided tape, carefully stick the SIM card onto the marked area, making sure that it completely matches the drawing. Don't press too hard, otherwise you won't be able to peel it off later.
Draw long horizontal, vertical and diagonal lines with a pencil or felt-tip pen. The dimensions of the format you need will be marked on the SIM card.
Trim the excess plastic as carefully as possible along the drawn lines.
Using sandpaper or a file, carefully trim the cut areas and round the edge as indicated in the diagram.
Remove the tape and insert the SIM card into the phone.

The whole process will take a few minutes, so take your time so as not to cut off too much. To make your work easier, there is a photo on the same template showing how to properly attach the SIM card. Don't be afraid, you will succeed.

Conclusion

Now you know how SIM card formats differ and how you can adapt them. Of course, contact a communication salon. But if you don't want to wait a long time, try cutting by hand using a template.

What SIM card format does your device support? How did you change the dimensions? Did you manage to do everything yourself? We are waiting for your answers in the comments.

Mobile communications have become our faithful companion. It's hard to imagine traveling by car, getting ready out of town, working, or even going to the store without a cell phone. The tube becomes a lifesaver in any difficult situation. A person is accustomed to his small communicator, and the connection that has been established between the cellular device and its owner is much stronger than that offered to you by the operator. Try not taking your cell phone with you for a couple of days. Thoughts about missed meetings, possible troubles while driving, or meeting anxiety will overwhelm you. This is how the body will react to the absence of 100 grams of plastic and semiconductors. If the cell phone is so important to us, then why do we know so little about it? Our series of articles “Secrets of Communication” should change this. We will introduce you to many interesting moments from the life of cellular communications and give you a basic understanding of the hardware.

Today we will talk about the SIM card. Most users do not pay any attention to this microcomputer. But without a shadow of embarrassment, we can say that the SIM card is the heart of your cellular device. The convenience and simplicity of this solution, on the one hand, bring it to the same level as the invention of the wheel. On the other hand, the SIM card has absorbed everything new from modern digital progress. The solution is not just a static device, but a serious evolving chip. The capabilities of which are far from being fully utilized.

Why SIM card?

The history of any device is closely connected with the question - “Why”? They say that if a child asks it at the age of 2, then he grows into a genius. If the cherished word is spoken at the age of five, then we have before us a simple individual. It becomes excruciatingly painful when you think about at what age we ask this question. So, by clearly answering why the SIM card was created, we will wash away the shame of the time delay of this issue.

Any cell phone must be uniquely identified by the operator's network. First of all, this must be done to withdraw money from him for the services provided. In addition, identification serves as the key to the provision of all services. When connected to the network, the handset receives a unique designation, which is entered into a special register. At first, the issue of assigning a code to each phone was resolved very simply. The operator used a unique Electronic Serial Number (ESN) - the serial number of the device. Most likely, this happened by analogy with the automobile industry. It is no secret that previously in many countries a license plate was assigned to a car at the factory and accompanied the car throughout its life (not to be confused with the body number or VIN number). This approach is entirely justified, even despite the obvious problems that are associated with the necessary agreements on formats and common databases. So, the first phones were online under their Electronic Serial Number (ESN). Problems appeared very quickly. More and more manufacturers of cell phones and equipment for mobile networks began to enter the market. It should be noted that they did not have warm relationships with each other, like any normal competitors in a dynamically developing market. Therefore, it has become almost impossible to agree on common Electronic Serial Number (ESN) formats. Of course, after some time this chaos would be brought into order. However, the thunder that struck from the users did not allow this scenario to develop. The fact is that in those days, visiting a cellular operator to register with it and other formal manipulations became a heavy duty for the subscriber. Cellular communications, which looked and presented as a sprout of freedom, appeared as a heavy burden. In a word, Electronic Serial Number (ESN) did not suit a certain audience at all. All efforts were thrown into searching for alternative routes. They were found. To be fair, I note that even now a number of networks in the world use Electronic Serial Number (ESN) to identify a subscriber, but there are no visible prospects in this direction and this approach is doomed to extinction. So, we dealt with the identified problem in a very interesting way. It was decided to separate the identification of the cell phone and the subscriber. Initially it looked extremely attractive. Over time, shortcomings appeared, which we will talk about later. So, the GSM standard imposed an obligation on cell phone manufacturers - each handset must have a 15-digit unique IMEI (International Mobile Equipment Identifier) number. There are special services that monitor and distribute number ranges for development companies. If you are familiar with computers, then this is an analogue of the MAC address of a network card. So, the cellular handset is recognized by the operator using the IMEI code. But the subscriber is separated from the cell phone. A SIM card is used to identify it. This device becomes an integral companion for all your conversations (except for calling emergency services by dialing 112, which is carried out even without a SIM card). Initially, the following requirements were put forward for this device:

separate module;
built-in memory and processor for executing commands;
programming capability;
finished goods

. All these conditions were met and one of the most popular microcomputers today hit the market.

Stages of SIM card development

Time stage	Evolution of the SIM card
Time stage	SIM card memory and supply voltage	SIM card functions
1991–1993	8 KB, 5.5 Volts	incoming and outgoing calls, call forwarding, call barring, call waiting, card blocking, PLMN network selection (roaming feature), SMS (reception only), speed dialing, sending and receiving fax messages, prohibiting work in networks without a roaming agreement - FPLMN.
1994-1997	8 KB; 5.5 and 3.3 Volts	Supports all functions of the previous window plus additional ones - PIN2 (data field protection), fixed dialing, SMS (added the ability to send), SMS status, auto-dial last number, menu language selection, message personalization, support for multiple numbers (voice, digital, fax) ), repeating the last number dialed, long numbers (more than 20 digits), displaying the service provider, Caller ID, anti-Caller ID, group call, creating a closed group of up to 10 subscribers, voice messages.
1997 to present	16 KB, 64 KB, 3.3 Volts; 1.8 Volts	It is in the formative stage. More than 50 new features have been added. Among them (the most interesting and promising) are SIM Application Toolkit, Enhanced Full Rate, as well as GSM and DECT interaction. Java support.

One simple pattern can be observed - the SIM card is becoming a more technologically advanced solution. The memory capacity grows along with the range of functions. What does the future hold for us? First of all, a jump in SIM card memory expansion is possible. Developers and engineers have repeatedly reported that they are ready to introduce a 1 MB SIM card to the market. However, this does not happen. What is the reason? New SIM cards cost more and someone will have to pay for them. No one will do this unless they see obvious benefits. Doubts come from the flash memory card market. They can become a universal repository of information. The cost of these solutions is significantly lower than SIM cards. In addition, the purchase of additional memory is a constitutional and democratic event, which means that when purchasing, the subscriber will not have to overpay for extra free space. And yet there is information that is not convenient to carry far from the SIM card, and the latter will still grow in digital volume. The second obvious step is to reduce the supply voltage. Work is underway here. These steps must be coordinated with cell phone manufacturers. Remember the GSM market 5 years ago, when new phones refused to work with old cards (or rather, the opposite - old SIM cards with new phones)? The inertia here is huge, but reducing the power increases the life of the cell phone, since the power spent on operating the SIM card becomes less.

SIM card under magnifying glass

So, it became clear to us that a SIM card is a subscriber identification module containing a microprocessor and memory in which various information can be stored. It meets all ISO 7816 specifications and operates according to the T=0 protocol ISO class A0h. This is a microcomputer based on an 8-bit processor. It is framed by three types of memory: ROM, RAM and EEPROM. Operators are very interested in the last component, which reaches 64 kb and can serve as a container for organizing service capabilities (SIM menu or SIM Service). Non-volatile EEPROM memory is programmed remotely (with the user's permission). Therefore, your mobile operator can add or remove new menu items to your phone via a message sent to you.

Now it has become clear how the operator creates new services on your phone. Everything is very simple. The situation is reminiscent of the operation of a regular computer. Remember that if the SIM card is removed from the handset, the information on it cannot be lost. On the other hand, it shouldn't surprise you that removing or changing the SIM card can change your phone's menu. Let's take a quick look at the memory structure of a SIM card. The root directory MF (Master File) contains subdirectories DF (Dedicated Files) and EF (Elementary File) files. Subdirectories, in turn, also contain files of the first and second levels. Each elementary file (EF) can belong to one of the following three families: transparent, linear, and circular. Elementary files contain a variety of service information. Such information can be the subscriber's IMSI code, a list of supported languages, a table of available services, etc. The file consists of a header and a body. The header describes in detail the structure of the file and the conditions for accessing it. The body contains the actual data.

A transparent file consists of a certain number of bytes, available individually and in blocks, for which it is necessary to specify their relative address (offset) and length (length).
A linear file consists of a sequence of records of a fixed length and should therefore be treated as sequential. The maximum size of such a file is 255 records per 255 bytes, not counting the extension.
A circular file contains a certain number of records of a fixed length. Moreover, each new entry always takes the first position, while the last one is “overwritten”.

The microprocessor of the SIM card is controlled by commands, like any other chip of the same class. We know of 18 teams. Perhaps there are undocumented ones.

So, a SIM card appeared before us, like a small computer. The device has a microprocessor that is controlled by commands. Information is stored in memory. Her organization follows strict rules. Does your computer sometimes crash? The SIM card is no different from it...

SIM card protection and malfunctions

The owner of the SIM card is able to make calls, transfer information or use other services. Its correct identification becomes the key to spending money. And where hard coins appear, you should definitely expect unscrupulous people who will try to rob you. This is the nature of human relationships at the top of the evolutionary path. Manufacturers try to give the user maximum opportunities to maintain control over their item. In other words, locks, ciphers, codes and guards are our best friends in this world. The SIM card also has its own lock. The key to it is the Personal Identification Number - PIN code. The user receives it when purchasing a card. You can enable (almost) all functions of the SIM card only by dialing it correctly. In case of an error (the user is given three attempts), identification does not occur and the card is blocked. You can bring it back to life only after entering the Personal Unblocking Key - PUK code (ten entry attempts). The PIN and PUK code was originally planned to be set to 8 digits. However, to make life easier for subscribers, the PIN code has been shortened to 4 characters. PUK consists of 8 digits. Some users remove protection from the SIM card. This is done through the phone menu. After this, the device does not require the owner to enter a PIN code when turned on or other associated events. There are also PIN2 and PUK2 codes. They help unlock additional capabilities of the SIM card. For example, they initiate commands to bar incoming or outgoing calls. Removing this code is also possible and responsibility for this step lies with the subscriber. Most often, according to service statistics, failures in the operation of SIM cards occur after they are mechanically damaged. The culprit of our review is very fragile. Modern cell phones have hard grips for SIM cards. Users diligently break them in the stubs. Replacing a broken SIM card is easy, but restoring the contents is often impossible. The second most common problem is forgetting your PIN code. After entering it three times, the phone is blocked. A dozen unsuccessful attempts to enter PUK and the SIM card turns into trash. A prompt appears on your cell phone screen to visit your operator to replace your SIM card. The pleasure is almost always paid and requires a passport for your identification. You are given a new SIM card and new codes for it. Very rarely, users report that their cell phone stops accepting the SIM card. A message appears on the screen that clearly indicates this. You can take out the SIM card, clean its contacts (ethyl alcohol will help do this, but you should not equate cleaning delicate gold contacts with removing rust from an old sheet of iron) and reinstall it into the mobile device. If the situation does not change, then feel free to contact the operator. Your SIM card, like any computer, is subject to failure. The situation is not very pleasant. The operator will exchange the damaged device for a new one absolutely free of charge (demand it), but all the information on the SIM card will be hopelessly lost for you. Personal experience suggests that all requests to restore it have encountered a wall of misunderstanding and an unequivocal assurance that this is impossible to do and this is not stipulated in the contract.

Attackers and your SIM card

Is it possible to clone SIM cards? Theoretically, this process can be solved quite simply. The attacker must copy the service information from the SIM card (International Mobile Subscriber Identity (IMSI), its individual encryption key (Ki) and the cryptographic algorithm program (A3)) to a blank blank. Thus, an absolutely identical clone will appear on the network, which will be able to spend money on the same basis as the original. Is it possible for a complete clone to exist on the network? A number of operators answer with absolute confidence that such a possibility is completely excluded. A subscriber with a double (one-time presence on the network) will be instantly disconnected until all circumstances are clarified. Indeed, operators maintain the user register very strictly. Catching multiplied subscribers is not difficult. However, recently an experiment was conducted (we are deliberately keeping silent about the operators and countries of this experiment) on cloning SIM cards. It turns out that some operators do not have protection for this case. Blind confidence in the impossibility of cloning GSM network users can play into the hands of attackers. How to clone a SIM card? Theoretically, to do this, it is enough to intercept a large data packet on the air. After that, extract the necessary data from there. In reality this method doesn't work. There is no way to force the phone to broadcast as much as needed. Therefore, you should only be wary of direct theft of your SIM card. Devices for reading and writing them can be bought in any large city without any licenses. Making a take requires a minimum of knowledge and only a few minutes. Therefore, beware of giving your SIM card into the wrong hands. Otherwise, information about your personal account may bring you a number of unpleasant surprises.

Instead of a conclusion

Let's summarize: a SIM card is an ordinary microcomputer. It is the heart of your cell phone and, unfortunately, this device is not infallible - it can break. In our review, we focused on talking about a SIM card for GSM networks. The devices used in satellite phones or networks of other operators are almost identical at a basic level. They may differ in memory size, command set, service information, and so on. In our next article we will tell you about how GSM communications are built in modern networks.

All questions, comments and suggestions can and should be asked at

It is unlikely that in our time there will be a person who has not held a SIM card in his hands at least once in his life. For most, this thing has become as familiar as a toothbrush.

Many people had to repeatedly replace their SIM card with a new one for one reason or another. And, nevertheless, for many it represents “something like that, without which you can’t call on cell phone.”

We will try to determine what a SIM card is in a smartphone, telephone or other mobile device, what functions it performs, as well as what types of it exist.

What is a SIM card

SIM card (Subscriber Identification Module) is a module that allows mobile communication networks to identify subscribers.

In most cases, it looks like a piece of plastic with contacts on it that allow it to be connected to mobile devices.

The plastic is durable and flexible, but can be easily cut if necessary, which allows, if necessary, to change the card format for installation in modern gadgets.

In addition to its main role as an identifier, a SIM card in a smartphone or telephone can perform a number of additional functions. For this purpose, the module provides an appropriate amount of memory, although it is very small.

As a rule, the SIM card memory stores a list of the subscriber's contacts, lists of received and missed calls, as well as the texts of SMS messages.

It is worth noting that the phone number is not stored directly in the SIM card memory; instead, the International Mobile Subscriber Identity (IMSI) is recorded there - the international identifier of the mobile subscriber, with which the number is subsequently associated with the mobile operator.

As a rule, SIM cards have two-level protection against unauthorized use. When you turn on your mobile device, the SIM card is activated after entering a short PIN code.

In the event of a triple entry error, the card is blocked, and unlocking is possible only after entering a long pack code, which is usually stored on the packaging supplied with the subscription package.

In case of several unsuccessful attempts, the SIM card is permanently blocked, and it is no longer possible to unlock it using the user’s means. Some people use SIM cards for which entering a PIN code is not provided.

Information stored in the card memory can be moved to the memory of a mobile device. Since the SIM card memory in a smartphone or even a telephone is only a small fraction of the total, this is a fairly relevant procedure.

What types of SIM cards are there in smartphones and other mobile devices?

At the moment, the most common are two SIM card standards: mini-SIM and micro-SIM, but in reality there are several more of them.

Why do device manufacturers go to all these lengths, continually creating problems for users of their products?

As a rule, the justification for such downsizing is the reduction in the size of gadgets, supposedly achieved through a small SIM card.

Whether this is true or not is difficult to say; it is unlikely that the extra millimeter won from plastic can cause a revolution in the weight and size characteristics of the device.

But judging by the available information, the next generation of 5FF SIM cards should already be built-in. In this case, the very idea of quickly changing the identification module turns into nothing.

Surely many are not delighted with this marketing policy of gadget manufacturers - but, alas, they are unable to change anything. In the meantime, these manufacturers are inventing ways to create additional problems for us, we will try to solve the current problems.

In particular, we’ll talk about what to do if the SIM card doesn’t fit into your smartphone.

How to change the SIM card size for a smartphone

The most “correct” way to adjust a SIM card to the requirements of a new gadget is to contact your mobile operator. To do this, you need to visit his office, having with you the SIM card to be replaced and an identity document.

There you will receive a multi-format card, from which you can easily get a SIM card of the required size, or a ready-made nano-SIM card, if that is what you need.

The obvious disadvantage of this method is the need to spend time visiting the office; many simply do not have time to do this. Therefore, people are looking for other solutions to the problem.

For example, many mobile phone stores provide SIM card cutting services. The same can be done at the service center, it all depends on which option is easier and faster for you to get to.

Using a special tool, your card will be adjusted to the required standard.

But even in this case, you will again have to go somewhere. And most of us would prefer to find a solution to the problem that would allow us not to leave the house at all and do everything from the comfort of our computer chair.

There is, in fact, such a solution. As a last resort, You can carefully trim the card yourself:

To do this, you will need a template downloaded from the Internet and printed on a printer, sharp scissors and fine-grained sandpaper.
The cut out template must be glued to the surface of the SIM card in accordance with the location of the contact pad.
After this, carefully cut off the excess plastic with scissors and clean the edges with sandpaper.

Many people are afraid of damaging its chip when squeezing out, or even cutting, the card. The fear is completely unfounded - SIM cards are designed for this kind of treatment, and damaging the chip is not as easy as it seems.

Although, of course, especially talented individuals are not even capable of such “feats.”

Smartphones with two SIM cards

Until a certain time, it was understood that there could only be one SIM card in a phone or smartphone.

However, over time, the dimensions of the devices decreased, and in 2009, General Mobile DSTL1 smartphones appeared on the market. They allowed users to use not one, but two SIM cards at once.

True, only one transmitter was provided in the design of the device. This meant that if both SIM cards can work in standby mode, then you can only talk on one of them.

Despite this, similar models soon appeared en masse in the lines of many manufacturers, especially young market players focused on the budget segment.

Such devices have found their audience among those who have to make frequent calls on the networks of several mobile operators.

In this case, using two SIM cards allows you to avoid increased tariffs when making calls to numbers of other operators. I had to pay for this with slightly increased battery consumption.

With the development of mobile Internet networks, another option for using dual-SIM smartphones has emerged. One card is used to make calls, and the second is used to surf the Internet.

However, it must be said that the popularity of smartphones with two SIM cards is not so high that all users switch to them, and single-SIM models have died out like dinosaurs.

In fact, the range of such devices on the market is not that large.

Moreover, the bulk of them are products of Chinese companies, such as Huawei or Fly.

However, this subclass of gadgets continues to develop: models have already appeared on the market in which you can use as many as three SIM cards, including models even from such a reputable brand as Samsung, which introduced the Galaxy Star Trios smartphone three years ago.

What to do if you lose your SIM card along with your smartphone

In the modern world, the telephone is not only a means of communication, but also very often plays the role of an identity card.

In this case, the role of the identifier, as mentioned above, is played by the SIM card. Therefore, if it falls into the hands of criminals, it can become a weapon for causing serious harm.

As soon as you discover that your SIM card has been lost, you must immediately take measures to block it. To do this you should:

Call the support center or visit the nearest communication center of your provider.
You must have your passport with you, since blocking is carried out only if the subscriber is reliably identified.
You may be asked for additional information, for example, the approximate card balance or the numbers of subscribers to whom you have recently made calls.

After this, you can relax a little and, without rushing, restore the SIM card:

This is done through the customer service center, where an application is filled out.
After submitting it, a check will be performed, if successfully completed, the employee will notify you when it will be possible to receive a new SIM card.
Sometimes this is done practically “without leaving the cash register.”
When you restore the card, not only your subscriber number will be restored, but also all the information stored on the card.

There are a lot of myths about cloning SIM cards on the Internet.

Allegedly, if you have the appropriate software, which can be purchased on the black market, you can create a clone card that will allow a cunning attacker to make calls on behalf of its real owner, receive messages and do all the other things that a SIM card allows.

In reality, there is very little truth in these myths. Indeed, theoretically, creating a map clone is possible.

However, since the late nineties, the vast majority of mobile providers have adopted a set of measures that make the use of such clones almost impossible.

So today there is no need to be afraid of evil hackers who can copy your SIM card and steal your hard-earned money.

The danger of hacking your phone via the Internet or wireless interfaces is much more real.