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What is dual SIM?

By Mint Fox

Originally published May 31, 2022


Last Updated March 21, 2024

Image of Mint Fox flashing devil horns in between a giant SIM card and a giant smartphone with an eSIM graphic on the screen.

Merriam Webster’s defines it as…just kidding. Dual SIM refers to a phone that can have two SIM cards at once. Those are considered dual SIM devices. Dual SIM means a phone can have either a physical SIM card and an eSIM, two eSIMs or two physical SIM cards. 

The newer generation of Apple iPhones, for example, feature dual SIMs and include a nano SIM and an eSIM. And phones are not the only devices that are capable of using two SIM cards–some tablets, including newer iPads, also allow you to have a physical SIM card or an eSIM. 

If you’re wondering what a SIM card is, we cover it with our guide on SIM cards, but basically it stores key data like your phone number. SIM stands for subscriber identity module. There are physical SIM cards, actual SIM cards you can hold and pop into your phone, as well as eSIM cards that are completely virtual. When these two come together is when you get that dual SIM magic in your dual SIM devices. Let me say dual one more time. 

Read on for more about dual SIM, how it works and all of its myriad advantages (and some disadvantages). 

In this article

How does dual SIM work?

To have two SIM cards, all you have to do is activate both your SIM cards whether you have a physical SIM card and an eSIM or two eSIMs. 

If you have two physical SIM cards, you’ll most likely have to swap them in and out unless you have an adapter. Not sure how to put in a SIM card? Check out our instructional video below.

Once your SIM cards are both activated, you’ll usually have to choose which number is your default number (for example, you can have one number for calling and texts and another for cellular data) and also assign different contacts to different numbers if you don’t want to constantly toggle between the two SIM cards. We cover the differences for iPhones and Android devices below. 

The three different types of dual SIM

Not all dual SIM compatible phones are equal. Today’s phones may allow you to use two at once, but some make you toggle between the two cards. Here are the three different types of dual SIM smartphones out there:

  1. Dual SIM passive: These types of phones can use two different SIM cards, but only one of them is actually working at any given time. If you want to use the other one, you’d have to activate it manually, making the first SIM card unusable for that time. That’s why this one is referred to as passive–one of the cards is always unusable until you switch.
  2. Dual SIM dual standby: This type of dual SIM means both of your SIM cards are active…but only when you’re not using them. Hence the “standby” name. Your phone will take calls for both, but if you answer the phone, you’ll start only using the SIM card attached to the number that was called.  
  3. Dual SIM dual active: This is the opposite of the passive dual SIM. Both SIM cards are active and working at the same time–always. You don’t have to worry about manually switching between the two different cards. 

Which brands offer dual SIM?

Nowadays? Most of them. Apple, Samsung, Google, LG and OnePlus all offer models that are dual SIM compatible.

Using Dual SIM on iPhones

What iPhone models are dual SIM compatible?

Since the iPhone XR and XS/XS Max models, iPhones have been dual SIM compatible. 

Can you have two phone numbers on one iPhone?

Yes, with dual SIM-enabled, you can have two separate numbers, like a business line and a personal line. In fact, this is one of the many advantages of having dual SIM compatibility.  

Is iPhone dual SIM?

Yes, any models after the iPhone XS/XS Max and iPhone XR allow for dual SIM compatibility. The latest model, the iPhone 13, even allows you to have two eSIMs. 

How does Dual SIM work on iPhone?

If you want to use dual SIM on an iPhone, iPhone 13 models allow you to have two eSIMs or a physical SIM card and an eSIM. For iPhone models 12, 11, and XS/XS Max and XR, you can use a physical SIM card and an eSIM. All you have to do is activate both plans, label them (e.g. one can be called “business,” the other “personal”) and then choose which one is your default number for calling/texting and cellular data. 

To activate an eSIM on your iPhone, all you need to do is scan the QR code your carrier provided and then add it when a notification pops up. For a physical SIM card, you just have to pop the new one into your SIM tray (curious what happens after that? Check out our guide on what happens when you switch your SIM card). 

After that, you can make and receive calls or send and receive texts from either number. You can even set it so certain contacts of yours will always be called by one number or the other. You can even switch numbers in the middle of a conversation just for kicks. 

Image of Mint Fox giving a thumbs up while holding a smartphone with an unlocked lock on the screen.

Can you use dual SIM on a locked phone?

No, to have two SIM cards, you have to have an unlocked phone. To learn more about what that means and how to unlock your phone, click the link. But for the TL;DR, an unlocked phone just means a phone that isn’t tied (i.e. locked) to a specific wireless provider. To be a Mint customer, for example, you must have an unlocked phone or unlock your phone.

Dual SIM vs eSIM

What is the difference between dual SIM and eSIM? Well, dual SIM just refers to the fact that some smartphones have the capability of having two SIM cards. Usually, at least one of those SIM cards will be an eSIM, which is a completely virtual SIM card—that is, one you can’t physically touch. Instead, it’s a programmable SIM card that does what a tangible SIM card does: it connects you with your network and gives you access to your service so you can use your wireless service.

What is the purpose of a dual SIM phone?

Usually the purpose of a dual SIM phone is so a person can have two separate phone numbers. This is great for people who own their own business, for example, and don’t want customers calling their personal line. But there are many other advantages that we list below.

What is the advantage of dual SIM mobile phones?

The advantage of dual SIM smartphones is that you can have two numbers–maybe one for work or one for your personal calls. Or one for your mom and one for everyone else, one for food deliveries and one for everyone else, etc. The possibilities are endless. You can also add a local wireless plan when you’re traveling abroad, or even have separate voice and data plans.

Here are some other advantages:

  1. If you use your phone for business, this is also a great way to see how much you’re using one line for business and distinguish between the two bills. 
  2. You don’t have to constantly swap in different SIM cards to achieve the same effect that a dual SIM compatible phone allows you. 
  3. In many countries outside of the United States, calls are free for those calling between the same networks. That’s why many people will buy two SIM cards from two different networks–so they can get some sweet savings on all those calls. This also helps if one of the networks has any outages since you’ll always be covered by one.
  4. One advantage of dual SIM compatible devices (like the new iPhones) is also that you don’t necessarily have to tote around two physical SIM cards if you’re using an eSIM as one of your dual SIM cards. 

What is the disadvantage of dual SIM mobile phones?

One disadvantage is that these types of phones can use up your battery a little faster because of all the increased activity. It does take a lot of power to run two SIM cards simultaneously. 

Here are some other disadvantages:

  1. Sometimes you aren’t able to actually use both SIM cards simultaneously. This is the case if you have a dual SIM passive card. 
  2. Also, sometimes if you have two SIM cards, there’s no option for you to insert an extra memory card for more storage space since the extra SIM card may use up that slot.
  3. Some popular apps you may want to use might not offer support for two SIM cards (for example, WhatsApp). 

Is dual SIM useful for travel?

Absolutely. With dual SIM compatibility, you can simply purchase a local SIM card when you’re traveling to spend less on calls, texts and other wireless essentials. You’ll also avoid roaming fees. And you don’t have to worry about taking out or deactivating your home SIM card. That’s what we call a win-win. 

Can I use one SIM card in a dual SIM phone?

You definitely can. If you’re a one number kind of person, there’s no need for you to have a second SIM card. It’s perfectly all right to have a dual SIM card and have just one SIM card activated. This also goes for other devices, like tablets. 

Is it possible to use multiple networks on a dual SIM phone?

Yes, it is possible to use two different networks. Some people will have a network for calls and one for everything else. Other people might also use a separate network when they’re traveling abroad, like a local one to get wireless essentials for a little less. 

As mentioned above, in other countries outside of the U.S., this is also very common since some foreign wireless providers offer calls free between people using the same networks. 

How do I activate dual SIM calling?

Well, that depends on your device.

To activate dual SIM calling on an iPhone:

  1. Activate your eSIM card (either the first or the second) by scanning the QR code your wireless provider gave you.
  2. Follow the prompts to set-up calls.
  3. Dual calling should already be enabled.

To activate dual SIM calling on a Samsung Galaxy:

  1. Open your Quick Settings panel
  2. Tap Calls
  3. Select which SIM you want as the default SIM for calls, or check the Ask Always option 

To activate dual SIM calling on other Android devices:

  1. Select Settings
  2. Tap Dual SIM & Mobile Network > Dual SIM & Cellular > SIM Card & Mobile Data
  3. Under the option Default Card Settings, tap Call (or Calling, on some phones) and choose your preferred default SIM card. As with the Samsung Galaxy, you can also choose an option to Ask Always when you pick up a call.

Ready for a duel dual?

Now that you know all about dual SIM, maybe you want to add another SIM to your phone. You can check out whether your phone is eSIM compatible by clicking that link. And if you’re wondering what dual SIM is, that’s when you and a fellow wireless user draw SIM cards at dawn to defend your honor. We’ll see you at dawn.

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