SIM card

SIM cards A SIM card is a device that acts as a module to identify a subscriber. Inside it looks like an integrated circuit that serves to store the international identification number (IMSI) and its key, which in turn is needed to identify and authenticate mobile equipment or personal computers and their subscribers. SIM cards also allow you to store contact information.

SIM cards must be on GSM phones, in CDMA devices they are needed for new models of devices with LTE compatibility. The SIM card does some of the work of a Universal Integrated Circuit (UICC), which is made of PVC with integrated pins and semiconductors. The SIM card allows data to be transferred between mobile devices over a distance.

SIM card formats

Sim cards are divided into 3 types based on their size:

1. Mini-SIM (full size).

Mini-SIM is called a standard uncut SIM card. Its dimensions are 25×15 millimeters. As a rule, such a SIM card was inserted into phones manufactured before 2011. Modern models do not support this SIM card format, but this does not mean that it cannot be used.

mini sim

2. Micro-SIM .

For the first time this SIM format was used by the company Apple in iPhone 4. The dimensions of the micro-SIM are 15×12 millimeters. Today, most smartphones support just Micro-SIM. After Apple Nokia began to use the SIM card, and then Samsung, HTC and other manufacturers.


3. Nano-SIM .

The latest generation SIM card and the smallest of all. Its size is only 12×5 millimeters. The card itself looks like a chip with a small plastic edging. The first time to use it Apple. The first phone that received Nano-SIM support was iPhone 5. After that Meizu and Samsung connected.


Visually, the differences between all types of SIM cards are as follows:

Differences in SIM cards in size

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Change SIM card with the operator

The easiest and most obvious way to reduce the size of a SIM card is to replace it in the company salon of a cellular operator. The process takes several minutes, and it's completely free, and the phone number won't change. The method can be problematic if:

  • If you need to save contacts. Make sure that the contacts are transferred to the phone's memory, or a backup is made, or in extreme cases write down the contacts with a pen, since the contacts saved in the SIM card will not be transferred to the replaced one.
  • Only its legal owner can replace his SIM card in any operator's salon – that is, the person on whose passport this SIM card is registered. If the card is donated by someone, then the card needs to be reissued in the communication salon. The consultant will not issue a new SIM card to a person who is not the legal owner, as this would constitute fraud.

After replacing the old SIM card or buying a new one, it will be in the form of a special Combi-SIM – this is a full-size card that can turn into a micro-SIM in a couple of seconds.

New sim card

Inside the micro-SIM / nano-SIM has a cutout along the contour. To get it, you just need to lightly press with your finger and squeeze it out of the larger border. There is no need to be afraid, it will break in the right places.

It is advisable not to throw out the frame itself – circumstances may turn out so that it can still be useful as an adapter for other phones in case of replacement.

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How to cut a SIM card for a phone

If there is a need to reduce your SIM card and not lose contacts, the only way is to cut the card. The most reliable way to cut a SIM card is to use a special tool – a SIM stapler (or SIM-Cutter, or a cutter).

This service is provided at the points of sale of mobile equipment or in the operator's salon. But you shouldn't wait for the card to be cut off for thanks. Everywhere they will demand a fee for this service and do not hesitate to knock out a check for it. As a rule, they require no more than 150 rubles. The cost includes the risks that the cutting SIM card bears, since if you carelessly damage the chip, without which the SIM card will not work.

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Cut yourself

If there are no staplers for SIM in the communication shops, some people manage to cut the cards themselves with simple scissors. Nobody teaches them this, everyone learns it on their own.

The procedure is very primitive. In addition to the fact that you need to be able to cut accurately, you need to know to what dimensions and along which line to cut. To do this, you need to have a special stencil template for cutting a SIM card.

Template for trimming SIM cards

To cut the SIM card to the required size:

  1. Download the template.
  2. Print it on A4 size.
  3. Select the desired SIM card format and cut it out along the contour.
  4. After cutting, we glue it to the SIM card for the convenience of cutting.
  5. Cut carefully.

This is how cropping to micro-SIM will look like:

Crop sim card to nano-sim

If the cut out SIM card does not quite fit into the slot in the phone, you can correct it with sandpaper or a sturdy nail file. It is extremely important not to hit the chip with the edges of the scissors, if it is damaged, it will refuse to work, and the SIM card will become unusable.

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Video: how to crop a SIM card

  • How to cut a SIM card for Micro-SIM with your own hands

You need to understand that not every card can be reduced in this way. The easiest will be to trim from mini-SIM to micro-SIM. Pruning to nano-SIM size will be more difficult as there is very little plastic left around the chip and there is a risk of scissors snagging the chip.

There are also old-style SIM cards with a large chip, such a card is difficult to turn even into a micro-SIM, and into a nano-SIM it is almost impossible due to the large size of the chip itself ..

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How to change the SIM card in the phone

There are a great many different phone models, and for each model it is not possible to describe the entire process of inserting and replacing a SIM card. But this process is very simple, and all gadgets can be divided into 2 groups:

  • Phone with SIM slot with special card holder (latest models).
  • Phone with a SIM slot in the housing behind the battery (older or budget phones are not smartphones).

For the first type, you can insert and remove the SIM as follows:

1) We take out the SIM holder with a special device in the form of a sharp tip, for this tip there is a special connector in the holder, insert the tip into this hole.

Open slot for sim cards and memory cards

2) We take out the holder for the SIM.

We take out the SIM holder

3) Change the SIM card.

Change SIM card

4) Insert the holder back into the phone.

It is worth noting that most new smartphone models have slots for two SIM cards, and they are of different sizes, and some have a slot for a memory card (micro-sd). But on the box from the phone or on the sticker it will be displayed: which SIM cards and where to insert.

Installing a SIM card for old type phones (with removable battery and cover) will be as follows:

  1. Disconnect the phone.
  2. Take out the back panel.
  3. Remove the battery.
  4. Find the SIM card slot. They have the shape of a SIM card and, as a rule, it is shown next to it how to insert the card.
  5. Install the battery back.
  6. Secure the rear cover until it clicks into place.

But what if you need to insert an already cut or reduced SIM card into a phone with a regular enlarged slot, or turn from nano-SIM to micro-SIM?

The easiest is to buy a SIM frame or special molds. Perhaps this was preserved when buying an old card.

SIM card frame

If it is not possible to purchase, you can make this frame yourself:

  • A SIM card of a regular size is taken.
  • Placed on cardboard of the thickness of the SIM card.
  • The map is outlined on the cardboard outside and cut out.
  • A micro or mini card is placed on the cut out cardboard, the contacts are aligned and outlined.
  • A place for a small SIM card is cut out in the cardboard from the inside.
  • The SIM card is inserted into the finished cardboard form, then, keeping it from falling, we insert it into the SIM card slot in the phone.

In this case, the cardboard form is only needed to restrict the movement of the SIM card, so that it does not lose contact with the phone.

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PIN code and PUK code

PIN (Personal Identification Number) is a code that is entered every time the mobile device is turned on (if PIN code protection is enabled on the phone). It serves to protect the phone from being used by unknown persons in case of loss or theft.

Today the PIN code is disabled on new SIM cards. You do not need to enter it when you insert a new SIM card into the phone.

The maximum number of attempts to enter an incorrect code is 3. After the third, the SIM card will be blocked. To unblock the card after such blocking, you need a PUK (Personal Unblocking Key) code. To unblock the SIM card and create a new PIN, you must enter the following combination: 05PUK1newPIN1newPIN1 #

If the PUK code is entered incorrectly 10 times, the SIM card is blocked forever.

These codes are usually located on the card where the SIM card is located when you buy it in a communication store. It looks something like this:

New sim card with pin and puk codes

PIN-2 and PUK-2 codes are needed to unlock some individual functions of the SIM card, but they are not used on modern SIM cards.

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ICCID (Integrated Circuit Card Identifier) ​​is a special international format code that is assigned to each SIM card, it is individual. This code is stored in the database of the operator providing communication services, and you can find it out. Sometimes the code is stamped on the SIM card next to the chip. In addition, it can be recognized via a smartphone.

To do this, go to the phone settings – find the item “About phone” – “General information”. If the information is not found in this way, you can use the SIM Serial Number application. ICCID looks like this:

ICCID for SIM card

In addition to the identification of the subscriber by ICCID, there is identification by IMSI – this is a special code that belongs to a particular telecom operator, and with the help of it it passes its exit to the international space. This is how the codes of Russian operators look like:

  • Russian Beeline28 2502834.
  • Russian Beeline99 2509934.
  • Russian Megafon 2500234.
  • Russian MTS10 2501034.
  • Russian Telecom 2509334.

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How to copy contacts and sms to a SIM card

Sometimes you need to transfer your contacts and messages from your old phone to your new one. To do this, you can use the data transfer to the SIM card. On most smartphones, the transfer process will look like this:

1) We go to the contact book.

Phone contacts

2) In the book, select the settings.

Contact settings

3) Select “Export contacts” or something similar.

Export contacts

4) Select the SIM and select the contacts that we want to transfer to the SIM card.

Selecting contacts to transfer

Modern SIM cards can store more than 250 positions of contacts and messages. But if there is a lot of data, you can use backup programs. In addition, software for a computer from a smartphone manufacturer allows you to copy data using a computer.

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How to unlock a SIM card when it is locked

It happens that the SIM card is blocked for a variety of reasons, it can be the subscriber's initiative or the operator's decision. The most common reasons for blocking a SIM card:

  • Self-locking (if the phone is lost).
  • Debt to the telecom operator.
  • Inactivity on this SIM card (not used or balance is not replenished for more than 3-6 months).
  • Wrong PIN entered more than 3 times.

Without operator participation, access can be restored only in the latter case using the PUK code. That is, after three attempts to enter the PIN-code, the device itself will ask for the necessary combination in order to enter the PUK-code of 8 digits there. The PUK code can be found in the same place as the PIN code on a special card where the SIM card was located when purchasing.

PIN and PUK codes for SIM card

In other cases, the most effective way to unblock a SIM card is to contact the operator's office and eliminate the reasons for its blocking.

In order not to go to the operator's offices, you can try to solve the blocking problems through your personal account on the website. All mobile operators have a personal account where you can manage the number and contact online support for help.

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Why the phone does not see the SIM card

Any phone and smartphone needs a working SIM card to work properly. And for this, the sim itself, a slot for it, a sim connector, as well as the necessary contacts must be in working condition.

Here are the most common reasons why the phone cannot see the SIM card:

  1. Expired card expiration date – one of the reasons may be long inactivity with this SIM card, more than 3-6 months, you need to get a new SIM card from the operator. Or the SIM card can be transferred to another person.
  2. Damaged SIM card – if it is constantly being moved from phone to phone, or has been unsuccessfully cut, and its chip is damaged, you need to change the SIM card with the operator.
  3. Locked phone – the device can be flashed to work only with a specific operator, before buying, you must definitely check with the seller.
  4. Broken SIM slot or damaged contacts – there can be many reasons for breakage, but most likely it will require qualified repair.
  5. Damaged OS in a smartphone – it happens that due to software failures, the phone does not see the SIM card, most likely, it will be necessary to flash the phone again.

If you cannot solve the problem on your own, the first step is to ask the operator if the phone number is blocked. If everything is in order on the operator's side, it is necessary to take the device for repair.

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