10 things to know about the sim card
10 things to know about the sim card
Written By: Alexandra Nuschele

A SIM card, also known as a subscriber identity module, is used in cellphones worldwide. It is a smart card that holds data for GSM cellular phone customers. GSM (Global System for Mobile Communication) is a digital mobile network widely utilized in Europe, Asia, Africa, and the rest of the globe. However, the United States is an anomaly, as it employs both GSM and CDMA technology (Code Division Multiple Access).

GSM phones can connect to any carrier’s network, decreasing costs for carriers and customers. GSM was made mandatory in Europe in 1987, and phones and equipment for these phones are less expensive to produce.

SIM cards are small cards with a chip that may be removed and transferred from one phone to another. A SIM card must be inserted into a GSM phone to connect to the local mobile network and make or receive calls or send messages.

Another benefit of using GSM is that any carrier must accept the calls or messages you send. For CDMA phones, the converse is true: you cannot move to a new phone without your carrier’s authorization. CDMA operators are not obligated to allow your phone onto their network.


  1. What Is the Meaning of “SIM”?

First and foremost, let’s go through the fundamentals. The term “SIM” stands for “subscriber identity module,” The name alone gives you a good idea of what a SIM card is for. It’s like a mini-passport that identifies you on the network and allows you to use cellular data.


  1. What is the Purpose of a SIM Card?

To switch on the phone, you don’t need a SIM card. Remove the SIM card from your phone and restart it to see whether this is true. It should switch on without a hitch.

Your phone, on the other hand, will not receive a signal. This is because your SIM card is in charge of storing all of the data needed to connect to the cellular network.

This information comprises the network to which you’ve subscribed, your phone number, and the amount of data you can use (3G, 4G, and 5G). As a result, removing the SIM card removes the information the phone requires to connect to the network, resulting in no signal.

Without a SIM card, you may still utilize non-cellular data, such as Wi-Fi. On the other hand, calls via Wi-Fi still require a SIM card because the data is finally handled by your network operator.


  1. SIM Cards are available in a variety of sizes.

Nano, Micro, and Standard SIM cards are available in three distinct sizes. Unfortunately, the size that your phone accepts is determined by the phone’s brand, model, and age. As a result, if you need a new SIM card, you must first determine which size your phone prefers and then buy one of those sizes.

Fortunately, the majority of cellphone operators have handled this situation well. When you order a SIM card from a well-known provider, you’ll be given a Standard-sized card. On the other hand, the SIM card will feature holes on the inside that allow you to take sections off of it to change it into its Micro or Nano versions.


  1. SIM Cards Aren’t Connected to a Specific Phone

When you insert a SIM card into one phone, it does not remain in that phone indefinitely. You may remove the SIM card and replace it with a new one when you upgrade your phone.

There are a few cautions here. For example, if your new phone requires a SIM card different in size from your present one, you may need to change your current SIM card or acquire a new one. And, sadly, some phones will just refuse to take your SIM card.


  1. You can only use a specific carrier’s SIM card on a locked phone.

When it comes to SIM cards, there are two terminologies to be familiar with: “locked” and “unlocked.” These two words determine which SIM cards can be used on the phone.

Only particular carriers’ SIM cards can be used in a “locked” phone. When a network provider partners with a device maker to give their customers exclusive access to a particular phone, you’ll see locked phones. If you put an incompatible SIM card into a locked phone, it will not function.

Another benefit of using GSM is that any carrier must accept the calls or messages you send. For CDMA phones, the converse is true: you cannot move to a new phone without your carrier’s authorization. CDMA operators are not obligated to allow your phone onto their network.


  1. SIM cards can store (some) data.

SIM cards can hold a small amount of data. However, before you try to pack your images onto it, remember that SIM cards can only save approximately 256kb of data, so you won’t be able to fit much on there.

Contacts and SMS messages are among the items that may be stored. This is useful when switching phones because you can bring all of your contacts with you instead of having to re-add everyone.

Some programs assist you to control the data on your SIM card if you’re interested in peeking inside. In addition, you may use them to view all of the information on your phone, which is helpful if you’re going to upgrade.


  1. You can replace a sim card.

Once you’ve determined where your SIM card is kept on your phone, inserting or removing it is simple. It might be hidden below the battery, depending on the phone. You’ll have to open the rear panel in such an instance. SIM cards for other phones may be located on the phone’s side.

If you have the correct tool, removing the SIM card is straightforward. Depending on what phone you have, you can simply pop it out of the slot with a paperclip or the edge of something like a credit card. Some SIM cards are in more accessible locations and can be slipped out with the tip of your finger.


  1. SIM cards can pose a security risk

Hackers abound, and SIM cards are no exception. Hackers target your SIM card because it contains your phone number, frequently connected to your email, social media accounts, and financial information. Calling a cell phone company and pretending to be you is one technique for hackers to acquire access to your SIM card. They may then transfer all of your personal information to another SIM card, insert it into their phone, and begin reading your text messages.

Fraudsters may quickly acquire access to your bank, social media accounts, or email since text messages can change passwords.

Whether you’re worried that your SIM has been hijacked, call your current phone from a different phone and check if it rings. If it stops ringing, you may have been hacked.

Setting up a PIN or password for your mobile account helps prevent hackers from gaining access to your account and impersonating you in person or over the phone.


  1. Some phones allow you to use two SIM cards at the same time.

As the name suggests, a dual SIM phone allows you to use two SIM cards in one phone. As a result, you may manage two different phone numbers on a single phone—one for each SIM.

This is an excellent option to keep your friend and family phone numbers distinct from your job phone number. In addition, when you put both your business and personal SIM cards in a dual-SIM phone, you may make calls to both numbers from the same device.

This also implies that you can make calls from either number. When you try to call someone, your phone will usually ask which SIM card you want to use to make the call.


  1. You should be able to use your sim card abroad.

When travelling internationally, certain data providers enable “data roaming.” This occurs when your cellular provider agrees with a firm in another country to allow your SIM card to utilize their network.

However, verify your carrier’s roaming rates before rushing out on vacation with your phone in your pocket. Some providers charge a significant fee for using data when travelling, which means you won’t be able to use your phone as freely as you would at home. Additionally, roaming inside some nations may be more costly than in others.

It can be worth obtaining a SIM card to save money when you reach your location. You’ll be paying the same rate as the citizens in this case.

An alternative to a SIM card is an eSIM, should you want to make international calls whilst travelling. eSim2go is for international travellers. Tourists and business travellers may save up to 90% on worldwide roaming costs by purchasing prepaid travel eSIMs from eSIM2Go. Try our eSIM right now!


Is my phone compatible with eSIM? 

To utilize eSIM, your phone must be freed from carrier constraints, regardless of your phone.

Some phones are locked to a single mobile network and can only utilize data plans from that provider.


eSIM-enabled computers 

Mobile phones aren’t the only devices that have changed and adopted new technology. PC computers have also joined the party and come equipped with a data SIM or eSIM card.

A list of PCs that support eSIM may be found here:

Microsoft Surface Pro X
Microsoft Surface Go 2
Microsoft Surface Pro LTE Advanced
Acer Swift 3
Acer Swift 7
Asus Mini Transformer
Asus NovaGo
Asus VivoBook Flip 14
HP Elitebook G5
HP Probook G5
HP Zbook G5
HP Specter Folio 13
Lenovo Yoga C630
Lenovo Miix 630
Lenovo Yoga 520
Samsung Galaxy Book 2

eSIM-compatible phones: frequently asked questions

Is the Samsung Galaxy S10 eSIM compatible?
The Samsung Galaxy S10 does not, unfortunately, support eSIM.

Is the iPhone 10 compatible with eSIM?
The iPhone 10 does not, unfortunately, support eSIM. The iPhone XR and iPhone XS were the first Apple phones to do so in 2018. Previous models aren’t compatible.

Is the Huawei P40 Pro + eSIM compatible?
The P40 and P40 Pro versions are the only compatible ones. However, it appears that the Pro+’s ceramic casing precludes this.

What should I do if my phone doesn’t support eSIM? How will I be able to use the internet while on the road? You can get a physical SIM card for your trips if your phone does not support eSIM technology. eSim2go international data SIM cards may be found here.

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