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How Does a Dual SIM Phone Work? What You Need to Know

Written by, Nikola Dimovski

Updated July, 19, 2023

How does a dual SIM phone work?

A dual SIM phone is an excellent option if you want more than one phone number on one device. This phone can hold two separate SIM cards and connect to two different networks, often at the same time.

Read on to find out more about the types of dual SIM modes and how you can set up a dual SIM.

What Is a Dual SIM Phone?

A dual SIM phone is a mobile device that has a SIM tray that supports two SIM cards and allows users to have two phone numbers on one phone.

With a dual SIM phone, you can make and receive calls and send and receive texts on both numbers

How Does a Dual SIM Phone Work?

Dual SIM phones have trays that can load in more than one SIM. 

Some dual SIM phones have regular dual SIM trays where you can place two different SIMs in separate SIM slots, while others have hybrid SIM trays, with one SIM card slot and one slot where you can either put a SIM card or an SD card. 

Because this type of phone allows users to use different SIM cards, you might be able to have two SIM cards from different networks on the same phone– provided that your phone isn’t locked to a certain provider

People who have dual SIM phones generally have to pick which number the phones would use to make calls and send texts. If they don’t, the phone will assign the SIM card in the primary slot as the main SIM. You would still be able to receive texts and calls when someone calls or texts you on the other number. 

Types Of Dual SIM Modes

The dual SIM mode determines how the user can switch between the numbers on their device. 

There are three different types of dual-SIM modes, including:

Dual SIM Passive

A phone with two SIM cards with dual standby technology allows users to have two different numbers on the same device but only use one of the SIM cards at a time. When one SIM card is active, the other one is unreachable. Users have to manually activate the second card if they want to use it (which would automatically deactivate the first SIM card).

Dual Active

If your phone features a dual-active mode, then you can use both SIM cards simultaneously. You will be able to make and receive calls from both cards, without having to activate (or deactivate) one or the other. 

For example, you could be on a call and receive a second call from the other SIM card.

Dual Standby

Dual Standby is a hybrid between dual active and dual passive mode. Namely, the SIM cards are both active but only when you’re not using them. That means you can receive a call or a text from one or the other SIM card, but you won’t be able to get a call or a text from the second SIM card while you’re talking on the phone using the first SIM card. 

Worth noting: If your phone doesn’t support dual SIM, there is a device called a dual SIM adaptor which you can connect to your phone to use two numbers on the same device.

How To Set Up a Dual SIM?

Newer smartphones don’t require users to manually activate SIM cards.

Once you place the cards in the SIM tray, all you’ll need to do is turn on your device. Your phone will ask which number to use when making phone calls or using data. There’s also an option to choose what number to use before every phone call and text.

But, if you have an older phone, you might need to manually activate your second SIM card.

Here’s how to do that.

If you’re an Apple user,

  1. Go to Settings.
  2. Select Cellular.
  3. Click on Add Cellular Plan.
  4. Choose a carrier.
  5. Enter your plan’s details.
  6. Tap Add a plan.

If you have an Android phone,

  1. Go to Setting’.
  2. Scroll down to Network & Internet.
  3. Select SIM cards.
  4. Choose a network mode.
  5. Select the preferred data SIM card.

Worth noting: The steps for setting up a dual SIM might vary from one phone to another. 

Benefits Of Using Dual Sim Phones

Although dual SIM phones tend to be more popular among people who need an extra number for work or business purposes, they are becoming more common. Here’s why.

Cut the hassle

One of the most important (and obvious) uses of a dual SIM phone is that it allows users to have two numbers on the same device. That means you won’t have to buy a second phone for your work number or carry it around, maintain, charge it, and keep an eye on two devices.

Get more coverage

A phone that supports two SIM cards means you can have more than one network option. This can come in handy if you often travel to places where your primary network provider doesn’t have enough coverage. 

Find a better deal

If you’re looking for a better deal and find it at a different provider, you could sign the contract without having to cancel your plan right away.

Avoid high roaming charges

A dual SIM phone is excellent for people who travel abroad. Having an empty SIM slot means you can purchase a local SIM card from the country you’re visiting and avoid roaming charges. 

Worth noting: There are also disadvantages of dual SIM mobile phones. They’re generally more expensive, consume more battery, and have a shorter standby autonomy.

Bottom Line

A dual SIM phone is just what it sounds like: a phone that has slots for two SIM cards. It allows users to have two different phone numbers on the same device and make and receive calls and texts on both. While they are generally pricer, dual SIM phones are an excellent choice for people who need a second number (usually for work) and want to cut the hassle of carrying two devices.

Frequently Asked Questions And Their Answers

What is the point of a dual SIM phone?

Dual SIM cards give users the option to have two different numbers and use them simultaneously on one phone. 

How do you switch between SIMs on a dual SIM phone?

The steps vary depending on the phone model. You’d usually have to go to Settings and look for Cellular (for Apple users) or Network & Internet (for Android users) and switch between the SIM cards from there.

How to know if someone is using a dual SIM?

The only way to tell if someone is using a dual SIM phone is to check the phone’s Settings.

Are dual SIM phones legal in the UK?

Dual phones are legal in the UK and in most places around the world. SIM cloning is illegal.

Do you need 2 SIM cards for a dual SIM phone?

A dual SIM phone will work with only one SIM card.

How does a dual SIM phone work?

A dual SIM phone has a SIM tray with two SIM slots and allows users to make calls, send texts, and receive calls and texts on both numbers.


My name is Nikola, and I’m an SEO Specialist and a tech enthusiast. I graduated from the Faculty of Economics, the department of E-Business Management. My experiences go from implementing ERP Solutions, CRM practices, and finally, on-page and off-page SEO. I take pride in staying ahead of the curve when it comes to SEO and keeping up with the latest changes to search algorithms. I love experimenting with new strategies and testing the results to see what works best. Outside of work, I enjoy tinkering with new tech gadgets and exploring the latest apps and software programs.