What is SIM Card and What Dose It Do? - SellUp - Blogs

What is SIM Card and What Does It Do?

What is a SIM Card?

SIM stands for Subscriber Identity Module. Its main function is to act like a portable memory chip that stores subscriber’s information and to connect devices to Global System of Mobile Communication (GSM).  A SIM card just looks like a small piece of plastic which will be inserted into your tablet or smartphone.  

sim card sizes

What is it used for?

The SIM card contains a unique identification number, the phone number, and other data specific to the user that it is registered to.

Without the SIM card inserted and working correctly, some phones cannot make calls, send SMS messages, or connect to mobile internet services (3G, 4G, etc) 

The ability to remove the SIM card from the phone provides a significant advantage for the subscriber to switch from one phone to another. In the scenario when the existing phone is damaged, the subscriber can immediately insert the SIM card into a new phone (provided the SIM card is not damaged). 

History of Sim Card

1991 – The first SIM card is the size of a credit card. They have storage size between 32KB to 128KB and stored SMS messages and phone book contacts. (32KB stores about five messages and 20 contacts). 

1996 – Mini-SIM. With the introduction of the smartphone, the increased demand for smaller devices that packed more power prompted the manufacturer to shrink the SIM card. Mini-SIM was introduced and used in most Android phones and flip phones.

2003 – Micro SIM, a smaller version which offers greater security and supports a more comprehensive phone book. Apple uses this on iPhone 4 to save precious room for its newest generation of smartphone. Micro-SIM was designed for backward compatible, which means the Mini-SIM can be used as long as the excess plastic is trimmed away. 

sim card history
2012 – Nano SIM, smaller and 15% thinner than Micro SIM. All iPhone 5 and later iPhone models use Nano SIMs. The only advantage over its predecessors – smaller. 

2016 –  eSIM 
The term "eSIM" simply means an embedded SIM card. It allow consumers to switch mobile operator without the need of removing physical SIM card. It also allows a simpler device setup without the need to insert or replace a SIM Card. This technology allows a wide range of connectivity across mobile-connected devices such as smartwatch, smart glasses, tablets, etc. Another advantage will be when traveling to places with different carrier services, it will be much easier to switch to a local network without losing a lot of time filling out forms and verifying your identities to the operator.

The Future of SIM Cards

In the end, we are going to see slimmer devices with one less compartment or slot to worry about. Devices will be more water and dust resistant because as we all know every single hole in the device compromises its resistance towards natural factors.

In terms of engineering, the devices could contain more tech inside or a bigger battery and who doesn’t love a bigger battery. One less slot in the Chassis on the smartphone body will be more resistant towards accidental or deliberate bending.

sim cards
In addition to smaller devices, we should see a lot of tablets and laptops opting for e-SIMs for seamless connectivity. Who knows if one day human will be implanted with a 'SIM' card in our body to allow full connectivity to the virtual world. 

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