How SIM Cards Actually Work


You most likely use it every day, yet if someone
asked you how it works, you’d have a hard time explaining it. I’m not talking about
Physics here, it’s all about your SIM card, that little chip in your phone. So let’s
figure it out! When was it invented? First of all, have you ever wondered what
SIM stands for? It actually means subscriber identity module or subscriber identification module.
The first SIM card in the world was developed in 1991 by the German company Giesecke & Devrient.
They sold 300 SIM cards to Radiolinja, a Finnish wireless network operator. In 1992, they sold
the first GSM mobile phone with a SIM card; it was a Nokia 1101. Today, it’s hard to
find a person who’s never used a SIM card – over 7 billion gadgets around the world
use them to make calls, send SMS and surf the web. Experts predict this number is going
to grow to 20 billion in the near future. The European Telecommunications Standards
Institute (ETSI) still holds the most SIM patents, but other private phone companies
also have some important patents thanks to which SIMs work. The largest manufacturer
of SIM cards in the world is the Gemalto company, with headquarters in Amsterdam and 15,000
employees. They’re now working towards the mass production of SIMs for 5G networks. The
first SIM cards cost more than one dollar each to manufacture. Today, they’re basically
worth a few cents apiece. But that price doesn’t cover design, development, inserting chips
into plastic cards and shipping them. Why do I need a SIM card? A SIM card has unique identification information
on it, like what mobile network it belongs to. It’s called an IMSI -International Mobile
Subscriber Identity. This unique ID connects your phone number with your gadget. When someone
is dialing your number, the call will go to the exact phone you have at the moment. SIM
also has its own memory. Even though it’s really small – just 64 kilobytes – it
can store around 250 contacts and some SMS. By the way, the same memory was in the Apollo
Guidance Computer used for the first Moon landings. If your SIM card is mobile, meaning you can
remove it and put it back into your phone yourself, you can also use it on different
phones. This comes in handy when your own gadget’s battery is dead, and you desperately
need to make a phone call from your number. Can my phone work without a SIM card? Technically it can, as a camera, or a device
that connects you to Wi-Fi, but not as a phone to make calls or text someone. For the absolute
majority of phones, a gadget without a SIM card is like a human without a brain. The
good news is, even if you seriously damaged your phone – smashed your screen or bent the
casing – you could still use the same phone number and keep your contacts. All it takes
is a SIM card transplantation. How does a SIM card work?
A SIM card basically looks like a little piece of plastic. It has an even smaller chip inside
that is its Microcontroller. It’s made out of silicone and plated with gold or other
metals to help it keep contact with the phone. The chip contains a processor, memory and
security circuits. Your mobile device reads the chip when you stick the SIM in it. It
contains the operating system for the card, can do some basic math, and stores important
information. This information is put on the chip on the production line. The most basic
types of that information are your International Mobile Subscriber Identity and a 128-bit key
called Ki (Key Identification). Those are basically your login and password in the mobile
phone world. All messages from your phone to the network are in a secret code. The key
to encrypt and decrypt messages is also stored on the SIM card. This provides communication
privacy. The SIM card chip also stores specific data, such as your card’s unique serial
number, the name of your cellular carrier, your PIN (if you’ve ever wondered what it
stands for, by the way, it’s your Personal Identification Number) to lock and unlock
the phone, PUK code from the carrier to unblock the phone and much more. Even your contacts
and last dialed numbers are there. Can someone track my location with the help
of a SIM card? This is a question of both privacy and security.
While it’s creepy to think someone can track your physical location for their purposes,
it’s good to know your phone can be found when it’s lost or stolen. And, it can also
be helpful when it concerns lost kids or elderly people, for example. So, a SIM card can help
to establish your location, but it’s only one player in the “find me” game. When
you insert a SIM in your cell phone, tablet, or even car, and turn the device on, it starts
connecting to cell towers to catch the signal. As you move around, your SIM works with the
towers nearest to you to provide the strongest signal. All these towers have known physical
locations. When phone companies or the police use their algorithms to find out how strong
the signal is from this or that tower, they can narrow down the search area significantly.
Services like “Find my phone” also use WiFi data to know a more specific location.
Of course, it’ll only work when the WiFi on your gadget is on. Add GPS information
to this, and you’ll get fairly accurate data on any gadget’s whereabouts in real
time. GPS will only be handy in this situation when you have cellular data enabled on your
plan or gadget. So if you want complete privacy, turn it off, along with WiFi, and tracking
you down using information from your SIM alone will be a challenge.
Do SIM cards break? SIM cards, like just about anything on this
planet, can get damaged or broken and don’t last forever. You’ll be the first to know
when that happens, as your phone will inform you the chip is defective. You won’t be
able to connect to your cellular provider in this case. Water is unlikely to be the
reason for that damage, though, since basically all new phones have sealed ports and jacks.
The SIMs themselves have always been waterproof. Why are SIM cards getting smaller?
The first SIM cards were around the same shape and size of a credit card. They worked fine
with the first mobile phones, but as mobile technology evolved and phones got smaller,
the SIM cards clearly needed improvement, too. Imagine fitting a credit card into an
iPhone – not the best idea, right? So fortunately, SIMs became smaller and more powerful at the
same time. First came the standard thumbnail-sized SIMs. They were standard until 2010, when
the Micro-SIM became universal. But even that SIM still had too much useless plastic. Some
people who upgraded their phones cut out the most important part with basic tools like
scissors. It was pretty risky since damaging the chip even a bit could ruin it all. In
2012, Nano-SIMs came into play, which are, in essence, just little chips with no extra
plastic around them. If you ever need to insert a newer generation SIM in an older phone,
there are special adaptors for that. The future of SIM cards
The latest iPhone models give you an idea of what all SIM cards will be like in the
future. They’ll be “eSIM”s, which means embedded SIM cards. Their size will be just
a fraction of a Nano-SIM. Forget the huge pieces of plastic and scissors you used to
cut out the chips! In fact, there’ll be no physical SIM cards whatsoever – instead,
they’ll be tiny chips on your phone’s logic board. The information on the chip will
be rewritable, so you’ll be able to change your carrier with a few easy steps. eSIMs
will be cloud-based, super secure, super fast and convenient to use. It’ll also be a win-win
situation for the manufactures: less distribution and installation costs, and better design
with more free physical space on your gadget! Losing one slot on your phone is also great
because it will ensure extra protection from water and dust getting inside. So, the new iPhones already have two SIM-cards:
one of the old school physical type and the other – an e-SIM that you can use with any
carrier you like. At what age did you get your first cell phone?
Let me know down in the comments! If you learned something new today, then give this video
a like and share it with a friend. But – hey! – don’t go anywhere just yet! We have
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video, click on it, and enjoy! Stay on the Bright Side of life!




Comments
  1. Nokia 5110 my first I was mad up with it at the time I had it in a leather case clipped onto my trousers now looking at it it’s a brick that Ariel but I’ll tell you now I wish my iPhones battery was like the Nokia it’ll stay changed for about a week maybe longer shout out from 🇬🇧

  2. Someone explain me why my phone got factory reset after insering working SIM card in it

    SIM was in a samsung s6 and went in a samsung a20

  3. I was 67 when I got my first cell phone. I never knew what a SIM card was or why it was important. I wonder if a new SIMs card would work in my old phone? I have a flip phone which i like as I can hear on it better than the "smart phone" I was given. Have to check that out

  4. E SIM will be super secure, super fast buy not mobile when the phone is out o charge mmmh? cant be placed in another phone i guess that will be the next thing to be developed or reinvented technology at its best

  5. Now I know there's more stuff I don't know. Good to know. Yabba Dabba Dooo. I was 79 when I got my 1st smart phone. Love YouTube, commenting & texting.😁😻🎈. 🐝 cool Dudes!

  6. Forehead or right hand… wonder if the SIM cards change with the new “5G Beast” system everyone is getting so sick from?

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