Why SIM cards suddenly stop working. Answer here

Has anyone ever, while standing in the communication salon, listened to the awesome story about the demagnetize
of a SIM card? I listened, twice .

For the first time, the five-year telenor SIM card failed, once it just stopped showing the network. The consultant said something learned: “Your card has become demagnetized ” – and in a couple of seconds, I made a new one. By the way, did not take the money.

This is not an exclusive “trick” of the green operator, most recently telenor gave me a new SIM-card, which did not even turn on. The diagnosis was the same, a piece of plastic was replaced and wished all the best.

But now there will be a sensation and disruption of covers: SIM-cards are not demagnetized ! Never. That’s it at all.

Those who always knew about it, respect, shake your hand. But a small survey on the tape of friends showed that most never thought about this “phenomenon.” But often for the replacement of a SIM card they ask for money. The amounts, of course, are small, something around 100-200 PKR, although, in most cases, the card can be restored with your own hands.

But first things first:

There is nothing to be demagnetized!

In fact, a SIM card is one of the types of processor ” smart cards ” that differ depending on the supported mobile communication system. The following discussion will focus on SIM-cards operating in our GSM networks.

To date, four sizes of SIM cards have been settled:

  1. Full-size (1FF), the size of a bank card;
  2. Mini-SIM (2FF), the usual big SIM;
  3. Micro-SIM (3FF), those that were in the iPhone 4;
  4. Nano-SIM (4FF), thin SIMs, which are now in most smartphones.

Buying a card now, you get a microcircuit on a universal piece of plastic that fits all these standards. And whatever the form of SIM-cards, they are united by one thing: this is a real computer in miniature . In a small chip with six contacts (there used to be eight), almost the same components as in a regular system unit fit. The SIM card has:

  • Processor (CPU);
  • RAM (RAM);
  • Permanent memory (ROM);
  • I / O controller (I / O controller);
  • File system.

Of course, there is no battery or some kind of human interface, they are simply not needed. But the small sim card has its own operating system, which allows you to store vital data for the phone, user files (contacts, SMS) and even Java applications.

Because of the desire to reduce the cost of components, operators issue cards with a minimum of memory, but technically, you can place gigabytes of information on SIM cards . Of course, nobody needs it, there are no terminals operating in this mode, and it is easier to operate with a large amount of data via USB.

Do you understand now? This is a board with contacts. There are no magnetized elements. The principle of data recording is not related to magnetism. Accordingly, there is nothing to be demagnetized.

What makes the phone lose network?

Usually due to wear. It seems you are thinking: “why should it break here?” – but in reality a SIM card, like any other electronics, can spoil:

???? Mechanical damage

Here the spectrum is wide: from the banal bias of the SIM card in the slot, to cracks and bent contact “whiskers”. Her contacts could be cut off from frequent replacement. Most damage is fatal to the chip, making it impossible to use the card for its intended purpose.

???? Corrosion or pollution

Metal tracks in the motherboards are subject to oxidation. But, in the case of a SIM card, the cause may not be water or condensed water. Remember how you usually change a SIM card – rarely anyone hesitate to touch it for the contact pad. And oily fingerprints are also corrosive.

⚡ Static voltage

Static electricity is lethal to most electrical components. Perhaps you are lucky in the square, and the tension is due to friction in your pocket. There are only a few such cases, but it is not worth sweeping aside this outcome.

???? Limited memory resource

Even the fancy modern SSD-drives are designed for a certain number of rewriting cycles. The resource of SIM-cards is also not unlimited, so be prepared to replace SIM cards in a few years when it is completely exhausted.

How to restore a SIM card?

If the card has broken, caught a static discharge or a resource has left it – alas, nothing can be done. Moreover, the numbers and SMS stored on this chip can not be recovered. You just thrown on a fresh blank SIM-card. But in most cases, the problem is in contact. Here is what you can do:

✏ Clean contact pad

Contaminants and small oxides are elementally cleaned with a regular office eraser. He quickly removes the resulting film or dirt, the main thing is not to brush the crumbs from the gum with his hands. For reliability, you can wipe the contacts with alcohol.

???? Check receiver contacts

Perhaps a small chip is not to blame for anything, and the nest itself is damaged in your phone. Contacts could be bent or jammed due to careless use. Alternatively, bend these “antennae” or put a piece of paper, but only if there is free access to the tray. In modern side-loaded smartphones, the sim card jacks are soldered into multi-layer boards, and such amateur work can turn a tube into a brick.

???? Transfer the card to another phone. And vice versa

Such an elementary test will immediately reveal the “guilty”. Just put the swap SIM-cards with another phone and see whose device is working.

Why all this?

I am absolutely not worried about the situation with SIM-cards, I just don’t want to listen to strange excuses every time. Why consultants talk about the mythical demagnetization, and not about the limited resources of the chip? Easier to explain ?

True, there were also those who accuse the operators of deliberately disabling the old cards, saying that it is impossible to hook up advertising without being noticed, and the operating system of modern sims allows this.

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