Curious why a SIM card is so important nowadays, and how could such a small thing be so powerful? It’s true – your device would be severely limited without it. And, just so you know, the source of its power is the golden chip itself. The plastic around it simply prevents the chip from coming in contact with other electronics in the device. By this point, you probably know you need to insert it into a SIM card slot in your device. But what does a SIM card do once you turn the phone on? Let’s find out.
SIM card does this:
1. Provides you with an identity on the network
The primary function of a SIM card is to give you a unique identity on a mobile network. It’s all in the name, after all – Subscriber Identification Module (SIM). When you turn the phone on, you gain an International mobile subscriber identity (IMSI). The IMSI is received by the network and cross-referenced in their internal database for Authentication Key (Ki).
After confirmation that the card is legitimate, and a generation of a second Authentication Key, the access is granted. That also means that your location can be tracked by reviewing the networks you accessed. You must’ve seen something like this in movies or crime documentaries.
2. Stores your billing information
Seems logical, right? Once you have a unique identity, the carrier can track your postpaid or prepaid SIM card and log all of its activities. Depending on the type, you can be billed at the end of the month or asked to pre-pay to get access to data. The bill stays accurate even if you go into roaming e.g. travel to a new country or access a new network.
3. SIM card gives you a unique number
By enabling the card and turning the phone on, you get a number that people can call or send text/multimedia messages to. When you can return the call or reply to the message, you know only the recipient will see it. As a consequence of this feature, more and more applications started using a phone number as a way to verify the identity or enable certain features.
4. SIM card allows you to access the Internet
When we discussed what is a SIM card used for, we mentioned that they enable your phone to access a GSM network. That means you can gain 2G, 3G, 4G, and soon, 5G Internet as long as you are inside the network. Granted, you need to enable mobile data and have a sufficient subscription plan. Furthermore, you can use your card as a hotspot. This allows other devices in the vicinity to recognize it as a wireless, portable router.
5. Stores your contacts, SMS, and even e-mails
This was a significant entry when we explained what will happen if you put your SIM card in another phone and what is stored on a SIM card. If you read those, you would’ve known that it can store between 8 KB and 256 KB of data. And, although most of it will be occupied by the carrier, you can still store quite a lot of contacts, a few important SMS, or even a couple of e-mails.
This seems very little when compared to today’s storage drives, we know. But, it allows for easy card swapping between two or more phones. Unless, of course, the SIM card is not working, but that can be fixed too.