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7 Things to Know About Your Phone’s SIM Card


Photo by Andrey Metelev on Unsplash

A Subscriber Identity Module (SIM) card is used in all smartphones around the world. You may not give your SIM card much thought until there’s a problem. For example, there’s something called a SIM card attack where a fraudulent actor uses a second SIM card to steal a victim’s phone number. They can then use it to reset passwords or gain access to financial accounts, including the ones requiring multi-factor authentication.

The following are seven things to know about your phone’s SIM card, so you can make sure you understand its importance and how to keep yourself safe from related attacks.

1. It’s Like a Small Passport

A SIM card is like a mini passport for using cellular data. The SIM card identifies who you are on a network as well.

Your phone relies on this chip to send text messages and make phone calls. If you don’t have a SIM card, your phone can’t connect to a cellular network. It can only work as an internet device, so you can still use Wi-Fi even without the SIM card.

The SIM card stores phone numbers, and you can transfer one between two phones, and then the new phone gets your phone number.

Phone companies typically provide SIM cards, and they may contain basic identifying information, like serial numbers. These let networks know what your phone number is and the carrier you use.

2. There Are Different Types of SIM Cards

SIM cards have become smaller and thinner, and they have more sophisticated electronics than in the past. There are currently several types of SIM cards. The mini-SIM is currently the standard. There are also micro-SIM, nano-SIM, and eSIM, which are embedded directly into a device and aren’t removable.

3. Some Phones Let You Use Two Simultaneously

There are some phones that are dual SIM, so if you manage more than one phone number, this feature might be especially helpful for you. You can put two SIM cards in one device, and then you’re able to manage two phone numbers, one per SIM, on a single device.

Some people might use a dual SIM phone if they want to keep their personal phone number separate from their work number.

Your phone will usually ask which SIM card you want to use to make a call if you have a dual device.

4. You Can Only Use a Certain Carrier’s SIM Card on a Locked Phone

There are two terms that are relevant when we talk about SIM cards. There’s unlocked and locked, and these are a reference to which SIM cards are available for you to use on the phone.

If you have a locked phone, it can only use a SIM card from certain carriers. If a network carrier partners with a device manufacturer to provide customers with exclusive access to a certain phone, then the device might be locked. If you try to insert a SIM card that’s not compatible, it won’t work.

Then, there are unlocked phones that allow you to use a SIM card from any provider. Mobile repair stores and phone shops can also unlock a phone that was previously locked.

5. You Can Probably Use Your SIM Card Overseas

Some data providers allow data roaming when you travel overseas. Data roaming is when your cell company will work with other international companies so your SIM card can use their network.

You need to check on the roaming charges of your company first, though. Some companies make it very expensive to use data abroad.

To save money, it might be worthwhile to get a SIM card when you’re at your destination, and then you’re going to pay for what the people who live there do to use their phones.

Your phone number will be different when you get a SIM card abroad, but it makes communicating easier.

If you have a dual SIM phone, you can keep your current SIM and also add a foreign one.

6. You Can Replace a SIM Card

It’s pretty easy to insert or remove your SIM card once you figure out where it’s at on your phone. It may be behind the battery, depending on your phone. In that case, you have to open the back panel to remove it.

On other phones, the SIM card is on the side.

You’ll need a certain tool to remove a SIM card if you want to make it simple. You can usually pop it out of its slot with a paperclip if you don’t have the tool. There are some SIM cards that you can slide out with your finger.

7. SIM Cards Can Be a Hacking Threat

Your SIM card is one of the biggest priorities for a hacker because it contains your phone number. Your phone number is likely linked to your social media, banking information, and email.

A hacker can gain access to a SIM card in different ways, including calling a cell phone carrier pretending to be you. If a hacker gets your SIM card, they can transfer all your personal data to another card, put it in their phone, and have access to everything on your phone.

You can reset passwords through your text messages, so at this point, it’s very easy for a bad actor to gain access to things like your bank accounts.

If you’re worried your SIM card has been hacked, you can use another phone to call yours. If it doesn’t ring, you may have been hacked.

Another way to know if you’re affected is if you completely lose service or get a text saying your SIM card has been changed.

You can set up a password or PIN associated with your mobile account to prevent hackers from impersonating you in person or over the phone. When there’s a PIN in place, they can’t gain access to your cellular service account.

If you think you are a victim, you should call your carrier immediately and let them know you didn’t make any changes.

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