Dove Comprare Una Sim Card

A Subscriber Identity Module (SIM) card is a flake inside well-nigh modern cellular phones that stores information your phone needs to communicate with your carrier's prison cell towers. SIM cards come in different sizes and if you were to remove the SIM carte from your phone you lot wouldn't be able to text, call, or admission annihilation on the internet.

What Is A SIM Carte?

Believe information technology or not, SIM cards have been on the scene since 1991. They were first developed by a German language manufacturer for a Finnish mobile carrier. Billions of SIM cards have been sold to appointment.

SIM cards are mandatory for phones connecting to the Global Arrangement for Mobile communications (GSM) networks, which is the telecommunications standard in over 193 countries that stores identification and security data on the card.

A SIM bill of fare is a small smart card made up of embedded contacts and semiconductors that has gone through four sizes over the years:

Full-Size (1FF or 1st Form Factor) was the size of a credit bill of fare; 85.6 mm x 53.98 mm.
Mini-SIM (2FF) was drastically smaller coming in at 25 mm x 15 mm first existence used in 1996.
Micro-SIM (3FF) made improvements in length with measurements of 15 mm 10 12 mm.
Nano-SIM (4FF) is the most recent form and is 12.3 mm ten eight.eight mm.

As phones got smaller and thinner, the demand for smaller components inside became more apparent. Having a carte the size of a credit card inside a device the same size wasn't realistic. Nowadays, SIM cards have been stripped down, removing almost all the surrounding plastic, and are essentially just a minor scrap.

The next-generation SIM technology is chosen an Embedded-SIM (eSIM). It's a not-replaceable chip soldered direct to your device'due south excursion board and contains something called "Remote SIM Provisioning," which allows customers to remotely actuate the due east-SIM on their devices. Correct now, Google's Pixel ii and the Apple Sentry 3 (forth with some cars), are the only real consumer tech using eSIMs, but that's expected to alter quickly.

What'southward Stored On A SIM Card?

A SIM bill of fare stores an International Mobile Subscriber Identity (IMSI) number, which is a unique 15 digit number identifying the card on carrier's mobile network. The IMSI is an important part of the lookup procedure and determines the network to which a mobile device connects.

Forth with the IMSI, a 128-bit value authentication key (Ki) is sent to verify your SIM with the GSM cellular network. The Ki is assigned by the operator and stored in a database on their network.

A SIM menu is as well capable of storing SMS messages and the names and phone numbers of upwards to 500 contacts, depending on the retention size of the SIM card yous accept. If you have to modify phones for whatever reason, you're able to transfer your contacts via the SIM card painlessly.

About SIM cards contain between 64-128 KB of storage.

How Does A SIM Work?

Essentially, a SIM bill of fare serves every bit your phone'south credentials to access the carrier network. Because the SIM holds this information, you're able to popular information technology into whatever phone with the same carrier, or an unlocked phone, to access the network.

Here'southward how it works:

When you kick up your device, it obtains the IMSI from the SIM, and then relays the IMSI to the network in order to request access.
The operator network searches the database for your IMSI and the associated Ki.
Assuming your IMSI and Ki are verified, the operator then generates a random number, signs information technology with your Ki using the GSM cryptography algorithm for computing SRES_2, and creates a new unique number.
The network then sends that unique number back to the device, which so passes information technology to the SIM to use in the same algorithm, creating a 3rd number. This number is then relayed dorsum to the network.
If both numbers match, the SIM card is deemed legitimate and is granted access to the network.

And then if you break the screen on your phone, while it's getting fixed you can accept your SIM out and put it in a replacement phone and withal access phone calls, texts, and data from your network.

RELATED: How to Unlock Your Cell Phone (And then You Can Bring It to a New Carrier)

Security

And so, what if your phone gets stolen? Can someone merely pop out your SIM bill of fare and stick it into another phone?

Well, yeah.

Someone could put that carte into another phone, and then use information technology to make calls, which can get quite expensive if it's used to make premium calls. If your SIM as well contains contact or other information, they will have access to that besides. The good news is that most mod phones do not store that kind of information on SIM cards.

Still, the first thing yous should do if your phone or SIM carte is stolen is written report the theft to your carrier. They can then block that SIM carte from existence used at all.

You can as well protect your SIM carte with its own Pin using the "SIM Lock" characteristic on your telephone. The characteristic locks the SIM bill of fare with a Pin so that the menu can't be used without unlocking it. Even though you set the feature using your phone, the Pivot is tied to the SIM card itself. Both Android and iPhone have this feature in the respected settings menu.

With so many SIM cards being actively used, they may just be the most used security token in the world. With your phone number being the key to ii-factor hallmark, hackers are always trying to effigy out ways to get hold of your telephone number so they can have control of your email, social media business relationship, and even your bank account. To practise this, they use a method called "SIM swapping," which allows them to take over anything tied to your number. By calling your mobile provider and pretending to be you, they trick the representative into sending a new SIM menu to them, gaining complete control.

How do you gainsay this technique? With some other PIN, of form. This time, you but call your carrier and ask them to add a security Pivot to your account. That fashion, anybody who talks to them to brand account changes (including you) must provide the Pin number start.

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