Everything you ever wanted to know about sim card

                                        

Sim Card

Sim card 

    What exactly is a sim card? do you know? You know that this little plastic piece in your smartphone comes out from the bottom of the battery or right side by pressing it with a pean, in which your cellular number is saved.

But what do you know more than this?

 

Sim card 

    Short answer:

 This is a Subscriber Identity Module, which most modern phones have a small circuit board to communicate with your carrier. In practice, it is a middleman between two pieces of hardware that allows both the baseband chip of the phone, and your carrier's cell tower, to be communicated.

    A SIM card can be easily changed from one phone set to another. The portability of data provides several benefits.

    You can put the SIM card in any phone with your phone number and plan; When you upgrade to a new phone, the SIM card can be replaced (as long as it is the same size).

    A SIM card is internationally recognized by its Integrated circuit card identifier (ICC-ID), which is engraved on the body of the card. It is also recognized by the carrier with its International Mobile Subscriber Identity (IMSI). Essentially, these two numbers tell the carrier that your phone is allowed to work on its network and, once connected, must be billed for certain features. Beyond recognition, SIM cards have many other functions.

 

SIM Full Form:

Full Form of SIM is -

Subscriber Identity Module or Subscriber Identification Module.

 

SIM Full Form 

Sim has a longer form - Subscriber Identity Module or Subscriber Identification Module.

 


Here are the dimensions of different types of SIM cards-


1. Full-Size (1FF or 1st Form Factor) - The size of a credit card was; 85.6 mm x 53.98 mm.

2. Mini-SIM (2FF) - Used for the first time in 1996, size - 25mm x 15mm.

3. Micro-SIM (3FF) - Micro-SIM improved the length with its measurement, 15 mm x 12 mm.

4. Nano-SIM (4FF) - Nano-SIM is the latest format and the size is 12.3 mm x 8.8 mm.

        As phones became smaller and thinner, the need for smaller components inside became more apparent. This size was not real due to the credit card size being the same inside the device. Nowadays, almost all of the plastic has been stripped of SIM cards, and is essentially a small chip.

        If you have an iPhone 5 or newer, your phone uses a Nano SIM. The iPhone 4 and 4S use large micro SIM cards.

    Samsung Galaxy S4 and S5 phones use micro SIM cards while Nano SIM is required for Samsung Galaxy S6 and S7 phones.

    Many carriers offer branded SIM cards with cutouts of all three modern sizes, so users can choose which size card they can put into their phone based on their device. There are also adapters so Nano SIM cards can fit in slots for Micro SIM or Regular SIM cards.

 

    A mini SIM card can actually be cut to convert it to a micro SIM, as long as only the plastic is cut.

    Despite the difference in size, all SIM cards have the same type of identification number and information on a small chip. Different cards have different amounts of memory space, but this has nothing to do with the physical size of the card.

 

Next-Generation SIM Technology:


        The next-generation SIM technology is called Embedded-SIM (eSIM). This chip cannot be changed and it rests directly on the circuit board of your device and contains something called "Remote SIM Provisioning," which the customer can remotely activate the e-SIM on their devices. Right now, Google's Pixel 2 and Apple Watch 3 (with some cars) are the only real consumer technologies using eSIM, but this is expected to change quickly.

 

Types of SIM Cards 


GSM and CDMA are two types of SIM cards:

 

1) GSM:

        GSM technology means Global System for Mobiles and its base can be given to Bell Laboratories in 1970. It basically uses a circuit switched system and divides each 200 kHz signal into 8 25 kHz time slots and operates in the 900 MHz, 800 MHz and 1.8M bands. It uses a narrowband transmission technology - basically time division access multiplexing. The data transfer rate varies from 64kbps to 120kbps.

 

2) CDMA:

        CDMA stands for Code Division Multiple Access which describes the communication channel theory that creates spread-spectrum technology and a special coding scheme which are time division multiplexing schemes and frequency division multiplexing schemes.

 

When did sim first appear?

        Believe it or not, SIM cards started appearing from 1991 onwards. They were first developed by a German manufacturer for a Finnish mobile carrier. Billions of SIM cards have been sold so far.

        The Nokia 1011 was the first GSM mobile phone to go on sale. Unlike earlier analog mobiles, GSM mobiles used digital technology for (relatively) interference-free communication, among other benefits.

 

How does sim card work?


    Basically, a SIM card serves as your phone's introduction card to access the carrier network. Because the SIM keeps this information, you can pop it into any phone with the same carrier, or unlocked phone to access the network.

 

Regard how it works:

Here's how it works:

    When you turn on your device, it receives the IMSI from the SIM, and then relies on the IMSI network to gain access.

    The operator network searches the database for your IMSI and the associated Ki.

    Assuming you have IMSI and Ki verified, the operator generates a random number, uses the GSM cryptography algorithm to calculate SRES_2, and signs it with your Ki, and creates a new unique number.

    The network sends that unique number back to the device, which then passes it to the SIM for use in the same algorithm, creating a third number. This number is then sent back to the network.

    If both numbers match, the SIM card is considered valid and network access is granted.

    So if you lose your phone, you can take out your SIM and keep it in a replacement phone and still access phone calls, text and data from your network.