A SIM card, also known as a Subscriber Identity Module, is a smart card that stores ID information that identifies a smartphone on a specific mobile network. The data contained in the SIM cards include user ID, location and phone number, network authorization data, personal security keys, contact lists, and stored text messages. SIM cards allow the mobile user to use this data and the features that come with it.
Without a SIM card, some phones will not be able to make calls, connect to Internet services such as 4G LTE or send SMS messages. SIM cards are removable and can be anywhere from, 32KB to 128KB.
What does a SIM card do?
Not all phones with SIM cards work the same way, however. Two different technologies are used; GSM (Global System for Mobile communication) and CDMA (Code Division Multiple Access). GSM is the most widely accepted digital mobile network. Network companies such as AT&T and T-Mobile use GSM. If a network operator uses GSM, that means users can remove their SIM card from the device and transfer it to another mobile device that has all the same data as their contacts. The network company will still be able to identify the user.
CDMA-enabled phones do not require a SIM card; instead, the mobile device will use an electronic serial number (ESN). Users with an ESN phone cannot switch between devices easily as users would need the permission of their network company. Network companies such as Sprint and Verizon use CDMA.
Even if carriers like Sprint and Verizon do not require SIM cards. SIM cards can still be found on devices located below those networks. This is because mobile devices require the use of SIM cards to use 4G LTE.
A device called a SIM card reader can be used to load data from the SIM card to a computer or other device.
SIM card types
SIM cards come in a variety of sizes over time. And SIM card types include:
- Standard SIM cards are 25x15mm and used on older and primary phones.
- Micro SIM cards weigh 15x12mm, and are likely to be available on phones from 2010 onwards.
- Nano SIM cards weigh 12.3×8.8mm and are used on new smartphones.
- eSIM, or embedded SIM, measures 6x5mm, and already has a SIM card in the phone. ESIMs are operated remotely by a network company.
Some phones now release dual-SIM support, meaning the user can have two different SIM cards activated on the same device. For example, the iPhone 10s supports dual SIM – one removable SIM card, and the other eSIM. Dual-SIM cards are useful for people who want to have two phone numbers on one device. For example, one job number and a private contact number.
How to check SIM card numbers?
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Benefits of SIM cards
The SIM card can be easily switched from one phone to another and this portable data offer many benefits. For example, a user who buys a new phone can insert a current SIM card to associate a new phone with the same number. And user preferences as the old one. In another normal situation, when the phone battery loses its power. The user can easily insert the card into another registrant’s phone for a loan without having to replenish the user’s minutes. Some retailers offer prepaid SIM cards that can give travelers local phone numbers, as long as their cell phones are not locked in a particular network company.
Security concerns
The personal SIM card can be cybercriminals as the SIM card has inaccurate access to personal emails, banking information, or social media accounts. Most of the time the password recovery option is sent via text or SMS. If the hacker accesses information stored on the SIM card, it may transfer the data to another SIM card.
SIM cards have a security code to prevent them from being used on a different device, so users can enter their phone settings. And change the SIM card PIN code to something more complex. Other security features include authentication and encryption to protect data and prevent listening.
