What is Sim card? Why do we need a SIM card? Is it possible to run cell phone without SIM card Why is it so important?
Today we will discuss about Sim card.
What is Sim card?
Sim card is a Subscriber Identity Module. In mobile’s world, there are two types of mobile mainly used for mobile subscribers genus. G S M & C D M A.
G S M (Global System for Mobile) : In just the SIM card is required to use the G S M phone.The SIM card is a small card. Which is fitted with a small chip.And it is a must need to work for every G S M phone.Without sim card the G S M phones never tap the network.All of the information is in the cards.
C D M A (code division multiple access) : Generally C D M A phones do not need a SIM.C D M A operator puts a complete list all of their phones. So that,they can access their phones to use network. Those phones are tracked by using E S A (Electronic Serial Number). That’s why, the phone does not need a SIM-card.After enabling C D M A phone, it is directly trying toestablish relationships with mobile network.
Most of the american mobile operatorprovides their service on C D M A-based service.However,some mobile operators are provided both C D M A and G S M service. But,G S M is most popular in the worldwide.
How does sim card work?
There are a lot of important data in the SIM card. Chief among them is the I M S I (International Mobile Subscriber Identity) AndAuthentication key (which validates I M S I). See the steps below to find out how does the system work:
- When the Mobile Equipment starts up, it obtains the International Mobile Subscriber Identity (I M S I) from the SIM card, and passes this to the mobile operator, requesting access and authentication. The Mobile Equipment may have to pass a PIN to the SIM card before the SIM card will reveal this information.
- The operator network searches its database for the incoming I M S I and its associated key.
- The network produces a random number (Think that the number is “X”.Then signs itwith the I M S I (and stored on the SIM card), computing another number (Think that,it is “Y”).Then the network sends the number to your SIM validity reviewed.
- Then your cell phone receive the number from networks and convey to the SIM. An authentication key has been added with this number. Thenit reached to the sim card andproduce a new number,(Think that which is “Z”). And it convey to the network again.
- The operator network then compares its computed “X” with the computed “Z” that the Mobile Equipment returned. If the two numbers match, the SIM is authenticated and the Mobile Equipment is granted access to the operator’s network.
What is SIM lock?
A Sim lock, sim lock, network lock or (master) subsidy lock is a technical restriction built into G S Mand C D M Amobile phones by mobile phone manufacturers for use by services providers to restrict the use of these phones to specific countries and networks. Unlock the phone means, Remove the certain limitation of the phone to use sim card. Many time, the lock phone may marketed for reducing the price of the phone and due to agreement between operator and phone company.
Prepaid sim card:
Another important facts you need to know about the Prepaid SIM card. There is no need to buy or subscribe any plan for this sim. It is much cheaper and affordable. In Bangladesh,mainly use prepaid sim card.However, there are many countries where people use post-paid SIM.
Thanks for reading. If you have interested in our article,we will discuss more about sim card. So,kindly tell use your mind by commenting…
See more article: