If we have a mobile phone then sim card is an integral part of it. SIM abbreviation is Subscriber Identification Module. It’s an integrated circuit that is used to store IMSI ( International mobile subscriber Identity ) number very securely. This IMSI number is used to identify the subscribers.
First sim card was manufactured in 1991 by a German company Giesecke & Devrient. And in 1992 world get its first mobile phone Nokia 1101. In starting every sim card manufacturing cost was around 1 doller but now it’s very small.
Use of Sim Card –
Every sim card has IMSI. That is an international mobile subscriber identity. The use of this identity is to connect your sim with mobile or existing gadgets. Whenever someone calls you, call will come on exact same number.
Memory size of sim –
Sim card has 64 kb ( Kilo byte) memory. I know that you are thinking about its small size of memory but it can save around 260 contacts as well as some massages too. In case of any damages of your device, you can take sim card out and put it in another gadget or mobile. In this way, you can access all contacts and messages saved in sim card. This process is called sim card transplantation.
Sim card working –
On a rough view of sim , it looks like a little piece of plastic. But if you see it properly, you will find that there is a chip, which consists microcontroller. It’s made of silicon and some layers of other conductors like copper, gold, etc.
The only use of these layers to make contact with gadget or mobile pins, then only gadget can read the sim card. If any other non conductive material layer is available on this chip then gadget will not read sim card. This chip consists of a processor and security circuits also.
When gadget reads the sim card , then the operating system of sim card will do some calculations and stores important information. This information is your IMSI and a 128 bit key. This key is called key only and uses for key identification.
This is just a login id and password, same like you are using while loging in to social media portals. All messages and data you are sending and receiving is in a secret code , that’s called machine language.
This key encrypt and decrypt the data so you can see the data in your language. This makes your communication extremely secure. Sim also consists some data like cards unique S/N ( Serial Number ) , the name of your cellular carrier ( Ex: Jio, Airtel, etc. ) , PIN ( Personal Identification Number ) to lock and unlock the phone and PUK to unblock the phone.
Tracking by Sim Card –
Yes it’s possible to track one person by his sim. If sim is live then it continuously send and receives signals to nearby mobile tower and try to connect with nearest tower. We can track one person by tower location. But person’s location is not precise. Based on the specific tower’s signal strength, we can get a rough idea of his location.
But if a person is using Wi-Fi then we can get the exact location of the person with the help of GPS ( Global Positioning System ).
Reason for Sim not detecting –
There can be any reason like water goes inside it or dust accumulated on its contact layer etc. If these are not a reason in your case then some internal circuit failure can be a reason. In these cases, you can request your service provider to change your sim. After that, you can use the new one.
Size evolution of sim cards –
Most of us have seen old sim cards. Those sims were big in size and called Standard sim card. Its size was 15*25mm. Then to reduce the space occupied by sim, makers trim some plastic area and make it smaller. This sim was named a Micro sim card. Its size is 12*15 mm.
After that to minimize the size of sim cards to max level , manufacture trims all plastic area and make sim as small as they can. Now we are calling it Nano sim card and its size is 8.8*12.3mm.
If you want to use Nano-sim or Micro sim in old mobile then we need to use some special adapter which is made of plastic and it will increase your sim size as per your requirement.
Future Estimation –
After seeing the evolution in sim cards till now, we can expect that in future we will see E-Sim. These sim cards will be inbuilt in Smartphones on its Main PCBA. This will provide effective waterproofing, Advanced security, and higher speed.
Hope you like this blog.