How do Sim card Work on phone


Sim Card is a very important object for us to communicate with each other today. So let us know how this Sim Card works.

The full name of Sim Card is Subscriber Identity Module.
This is usually a small computer. Sim Card has some special functions that we need to know.

Identity Verification: 

The important function of Sim Card is to identify you following the subscription.So if you send an SMS, make a Phone Call, send a Video, based on this Sim Card instructs your service provider to make a bill.

This whole process is done by IMSI (International Mobile Subscriber Identity). It is an identity verification process. It can be said that this is a login process.

When you turn on your phone, then from IMSI to Information Sim Card and then from Sim Card to Network. Then your network will look for all the information from IMSI and the key to verify your identity.

The network then generates a random number which we call "X" and signs it with your identification key to generate a new number "Y".

Then Network "X" will send to your phone, Phone will send to Sim Card again. Sim Card then signs the identification key to create a new Number "Z".

Then "Z" is sent back to Network.

If the "Y" of the Network matches the "Z" of the Sim Card, then the Sim Card is marked as valid and a signal is sent to the Network to call and use the data

This is a very complicated process, because it happens in a very short time, and it is also possible if you want to get this service on another phone as long as your Sim Card is not locked.

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Technical breakdown:

How Does sim Card Work

If you look at this picture, you will see that the Sim Card is divided into many ways and. 

Each of these parts is called a different Pinout.

  • Pin 1 to connect to the phone's power supply.
  • Pin 2 is used to reset the SIM.
  • Pin 3 Sim provides Clock signal for its Processor.
  • 4 and 8 pins are reserved for future use.
  • Ground of Pin 5 Chip.
  • Pin 6 is used to communicate with any NFC enabled mobile phone.
  • Pin 7 controls the connection between Phone and Sim.

The processor handles applications such as identifying you and ensuring you are on the right network. It also works like storing Contact and SMS information in SIM Memory.

SIM cards allow a mobile user to access this data and related features.

You will not be able to make phone calls, connect to internet services or send SMS messages without a SIM card. SIM cards are removable and have devices.

Each SIM card has a different frequency. Different frequencies like 4G SIM card and 3G SIM card work in two ways and this is the main reason for noticing the difference in speed between 4G SIM and 3G SIM card.

There are two types of SIM technology:
  • GSM (Global System for Mobile Communications).
  • CDMA (multiple access to code section).

GSM is the most widely used technology in digital mobile networks.
GSM technology using ASTT and T-Mobile.

GSM technology users will not be able to change and transfer SIM cards from one device to another.It does not allow transfer of the same data and contacts to another mobile device.The network provider will still be able to identify the user.

CDMA enabled phones do not require a dedicated SIM card; In this technology the mobile device will use an electronic serial number (ESN).

Users switch the SIM card with ENS number to the device, if users do not have an ENS number they need permission from the network carrier if

Sim Card is a complex device, so hopefully we have been able to explain the workings of Sim Card to you properly.


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