In the world of mobile phones, there are two primary phone types available to consumers: GSM (Global System for Mobile) and CDMA (Code Division Multiple Access). GSM phones use SIM cards whereas CDMA phones do not use SIM cards.
SIM cards are small cards that contain a chip that you have to insert into a GSM phone before it can work. Without a SIM card, a GSM phone will not be able to tap into any mobile network. The card contains all the important information.
In this way the customer ID is linked to the SIM card and not to any mobile phone. That's why you can use the same SIM card between different GSM mobile phones. SIM cards are only used on GSM phones, in case of CDMA mobiles they are required only for new LTE enabled handsets. SIM cards can be used in satellite phones, smart watches, computers, or cameras.
What does a SIM card do? (What Does a SIM Card Do?)
What information does the SIM card hold? The most important bits of data include the IMSI ((International Mobile Subscriber Identity) and the authentication key that validates the IMSI. The carrier provides this key.
On startup, the phone receives IMSI from the SIM card and relays it over the network.
The network takes the IMSI and looks in its internal database for the known authentication key of that IMSI.
The network generates a random number, A, it signs it with an authentication key to generate a new number, B is the response it would expect that the SIM card is valid.
The phone receives A from the network and forwards it to the SIM card, which signs it with its own authentication key to generate a new number, C. This number is sent back to the network. Is.
If the network number matches the number C of the SIM card, the SIM card is declared valid and access is granted.
The data not only determines which network to connect to, but also acts as the "login credentials" that allow the phone to use the said network.
Switch Phones With a SIM Card
For this reason, SIM cards are actually quite convenient when it comes to switching phones. Since your subscriber data is on the card itself, you can plug the SIM into a different phone and all will be well. On the other hand, it is more difficult to switch phones with a CDMA carrier because the phone itself is the entity that registers with the network.
Each SIM card has a unique identifier called ICCID (Integrated Circuit Card Identifier), which is stored in the card. ICCID consists of three numbers.
SIM cards are also capable of storing other information, such as contact lists and SMS messages. Most of the SIM cards have a capacity between 32KB to 128KB. Transferring this data mainly involves removing the SIM card from one phone and inserting it into another, although this has become less important with the advent of backup apps.
What is Locked SIM Card? (What is a Locked SIM Card?)
SIM card lock is a very important security feature, which you will easily find inside the security option in all mobile phones. I can set a password, with the help of this, no one can use your SIM without a password, once the SIM card is locked, then after this, you will put this SIM in whichever phone and whenever the phone is switched on. ) then your phone will accept the SIM password (Enter sim pin).
તમારા આધાર પર કોઈએ SIM કાર્ડ નથી લીધા ને? આ રીતે કરો ચૅક video અહિંથી જુઓ
You can use this SIM only if you know the password of the SIM, otherwise you cannot use it. But here if you enter the wrong password 10 times in the SIM PIN, then after this your SIM card will be locked and you will
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