Can You Use Two SIMs at the Same Time? Travel eSIM & Dual SIM Explained
Updated: 3 days ago
Using a travel eSIM doesn't necessarily mean switching off or removing your normal UK SIM.
On many modern smartphones, you can have two SIMs active at the same time. This is known as Dual SIM, and it can be particularly useful when travelling abroad.
You can keep your usual UK number available for calls and text messages while using a travel eSIM for mobile data. That means you don't have to choose between staying reachable on your normal number and avoiding expensive mobile-data roaming charges.
The important part is setting your phone up correctly before you start using data abroad.
Quick Answer: Can You Use Two SIMs at the Same Time?
Yes, if your phone supports Dual SIM.
A common travel setup is:
Your normal UK SIM: kept active for your existing phone number, calls and SMS messages.
Your travel eSIM: used for mobile data while abroad.
Many recent iPhones and Android phones support either a physical SIM alongside an eSIM or, on compatible models, two active eSIMs. Apple and Google both provide Dual SIM functionality on supported devices.
However, the exact capabilities depend on your phone model and mobile networks, so check that your device supports the combination you intend to use before travelling.
What Is Dual SIM?
Dual SIM simply means that a phone can use two mobile plans.
Traditionally, this meant having two physical SIM cards. With the arrival of eSIM technology, many phones can now combine a physical SIM with an eSIM or use two eSIMs simultaneously.
For travellers, that creates a particularly useful arrangement.
You can leave your everyday SIM installed and add a separate travel eSIM before your trip.
Instead of replacing your UK SIM, the travel eSIM effectively sits alongside it.
For example:
UK SIM → calls, texts and your normal number
Travel eSIM → mobile data abroad
Your phone's settings allow you to decide which SIM performs which job.
Why Use Your UK SIM and a Travel eSIM Together?
The main advantage is convenience.
Your normal mobile number may be connected to far more than telephone calls. You may use it for:
Calls from family and friends
SMS messages
Banking verification codes
Two-factor authentication
Work contacts
Booking confirmations
Other services linked to your mobile number
Removing or disabling that SIM completely may make some of those services less convenient.
Using Dual SIM allows you to keep the UK line available while using a separate eSIM for internet access.
That can give you the best of both worlds: your familiar number remains available while your travel eSIM handles your data.
Can You Keep Your UK Number While Using a Travel eSIM?
Yes.
Installing a travel eSIM does not normally change the telephone number associated with your existing UK SIM.
Your normal SIM remains a separate mobile plan.
This means that, with the appropriate Dual SIM settings, you can continue using your usual number while travelling.
Which SIM Should You Use for Mobile Data?
When travelling, you will normally want to select the travel eSIM as your mobile-data line.
On an iPhone using Dual SIM, Apple allows you to choose which line is used for cellular/mobile data. Google Pixel phones similarly allow you to select a default SIM for mobile data.
A typical setup might therefore look like this:
Primary/UK SIM: calls and SMS
Travel eSIM: mobile data
Once configured, apps such as Maps, Safari or Chrome, email, social media and messaging services can use the internet connection provided by the travel eSIM.
Should You Turn Off Data Roaming on Your UK SIM?
This is one of the most important settings to check.
If your intention is to use the travel eSIM for data, you generally don't want your UK SIM unexpectedly using mobile data abroad and generating roaming charges.
You should therefore check the roaming arrangements of your UK mobile plan and configure your phone accordingly.
On supported phones, the roaming setting can be managed separately for each line. Apple also warns that roaming charges can still occur if data roaming is enabled on a line while you're outside the area covered by that plan.
Don't simply assume that installing a travel eSIM automatically prevents your UK SIM from roaming.
Be Careful with Automatic Data Switching
Another setting worth understanding is mobile data switching.
Some phones can automatically switch between your two SIMs under certain circumstances.
That can be useful at home, but when travelling it may not always be what you want.
For example, Apple offers an Allow Cellular Data Switching setting, while compatible Google Pixel phones provide automatic data-switching options.
If your aim is specifically to prevent your UK SIM from using chargeable roaming data, check these settings carefully rather than assuming all internet traffic will automatically stay on your travel eSIM.
Can You Still Receive Calls on Your UK Number?
Potentially, yes.
Keeping your UK SIM active can allow your normal number to remain available for incoming calls.
However, receiving or making conventional mobile calls abroad may still attract roaming charges from your UK network.
Dual SIM doesn't make roaming charges disappear. It simply allows two mobile plans to coexist on the same phone.
Before travelling, check your UK network's charges for your destination if you expect to make or receive traditional mobile calls.
There are also some technical differences in how phones handle simultaneous calls on two lines. These vary according to the device, network and whether features such as Wi-Fi Calling are supported.
Can You Still Receive Text Messages?
In many Dual SIM setups, yes.
This is one reason travellers may choose to leave their home SIM active.
Receiving an SMS verification code from your bank, for example, can be useful even if virtually all of your internet use is going through the travel eSIM.
But again, check the roaming terms of your own UK provider. Charges and functionality can vary by network and destination.
What Happens to WhatsApp When You Add a Travel eSIM?
Usually, very little.
WhatsApp is linked to the telephone number you registered with the service, but it uses an internet connection to send and receive messages.
Adding a travel eSIM for mobile data doesn't automatically change your WhatsApp number.
You can therefore typically continue using WhatsApp with your existing number while its internet connection is being provided by the travel eSIM.
There is normally no reason to register WhatsApp again simply because you've installed a travel eSIM.
Can You Make Calls Using the Travel eSIM?
That depends on the eSIM plan you've purchased.
Some travel eSIMs are primarily or exclusively data plans and don't provide a conventional mobile telephone number for standard voice calls and SMS messages.
That doesn't mean you can't communicate.
With mobile data available, you can still use internet-based services such as:
WhatsApp
FaceTime
Messenger
Teams
Other internet calling and messaging apps
If conventional telephone calls are important to you, check what the particular travel eSIM includes before purchasing it.
How to Use Dual SIM on an iPhone When Travelling
The exact wording can vary slightly by iOS version, but compatible iPhones allow you to manage your lines through Settings → Mobile Data/Cellular.
You can label your plans to make them easier to recognise — for example:
UK
Travel
You can then choose which line handles mobile data and which line is your default for voice calls.
Apple specifically identifies adding a local data plan while travelling as one of the uses for Dual SIM.
Before leaving the UK, check that you understand which line has been selected for mobile data.
How to Use Dual SIM on Android When Travelling
Android settings vary more between manufacturers, so the exact menu names depend on your phone.
On Google Pixel phones, for example, Dual SIM controls are found under Settings → Network & internet → SIMs. You can choose which SIM is used for calls, texts and mobile data.
Samsung and other Android manufacturers provide similar SIM-management controls on compatible devices, although the terminology and menus can differ.
The principle remains the same:
keep your home SIM available and select the travel eSIM for mobile data.
When Should You Install Your Travel eSIM?
Where your provider allows it, installing the eSIM before leaving home is often easier than trying to do everything after you arrive.
You have familiar Wi-Fi available, you're not tired after a flight, and you have time to resolve any installation problem.
Installation and activation aren't necessarily the same thing.
Some travel eSIMs can be installed before departure but should only activate or begin their validity period according to the provider's instructions.
Always check the instructions supplied with your particular eSIM.
A Simple Dual SIM Setup for Travelling Abroad
If you want to keep things straightforward, a typical configuration is:
UK SIM
Keep the line active.
Keep your normal telephone number.
Use it for calls or SMS where required.
Check your network's roaming charges.
Prevent unwanted mobile-data roaming.
Travel eSIM
Select it as your mobile-data line.
Enable the settings required by the eSIM provider.
Use it for Maps, browsing, email, WhatsApp and other data services.
Monitor your travel-data allowance where applicable.
The exact settings depend on your phone and mobile plans, but thinking of the two SIMs as having separate jobs makes Dual SIM much easier to understand.
Common Dual SIM Travel Mistakes
Dual SIM is convenient, but a few simple mistakes can lead to unnecessary problems.
Watch out for:
Selecting the UK SIM rather than the travel eSIM for mobile data.
Leaving chargeable data roaming enabled on the wrong line.
Allowing automatic data switching without understanding what it does.
Assuming a data-only eSIM includes a normal telephone number.
Switching off the UK SIM and then discovering you need an SMS verification code.
Assuming all incoming calls are free while roaming.
Installing an eSIM without checking whether the phone is compatible or unlocked where required.
Activating a travel plan too early when its validity starts on activation.
A few minutes spent checking your settings before departure can prevent most of these issues.
Dual SIM Travel Checklist
Before you travel:
Check that your phone supports Dual SIM and eSIM.
Install your travel eSIM according to the provider's instructions.
Give each SIM a clear label such as UK and Travel.
Select the travel eSIM for mobile data.
Check the data-roaming settings for both SIMs.
Review any automatic data-switching setting.
Check your UK provider's roaming charges for calls and texts.
Confirm when your travel eSIM's validity period begins.
Make sure you know how to switch back to your UK SIM for data when you return home.
Frequently Asked Questions
Can I Have My Normal SIM and an eSIM Active at the Same Time?
Yes, on compatible Dual SIM phones. Many devices allow a physical SIM and eSIM to be active together, while some newer devices can support two active eSIMs. The precise capability depends on the phone and network.
Can I Keep My UK SIM Active While Using an eSIM Abroad?
Yes. This is one of the main benefits of using Dual SIM when travelling. Your UK SIM can remain available while the travel eSIM is selected for mobile data.
Which SIM Should I Use for Data Abroad?
If you've purchased a travel eSIM specifically for overseas data, you would normally select that eSIM as your mobile-data line.
Will My UK SIM Still Receive Texts?
It can remain available for SMS on a compatible Dual SIM setup, although network availability and your provider's roaming arrangements still apply.
Will WhatsApp Still Use My UK Number?
Normally, yes. Adding a travel eSIM does not automatically change the number registered with WhatsApp. WhatsApp can use the internet connection supplied by your travel eSIM.
Does Dual SIM Stop Roaming Charges?
No. Dual SIM itself does not prevent roaming charges. You still need to configure the phone correctly and understand the roaming charges associated with your home mobile plan.
Can Both SIMs Use Mobile Data at the Same Time?
Typically, one line is selected as the primary mobile-data line at a time. Apple states that iPhone uses one mobile data network at a time, while Google Pixel similarly allows one SIM to be selected as the default for data, subject to additional switching features on compatible devices.
Do I Need to Remove My Physical SIM to Use a Travel eSIM?
Usually not if your phone supports Dual SIM. One of the advantages of eSIM is that you can add another mobile plan without physically swapping your existing SIM.
Final Thoughts
For many travellers, using two SIMs together is one of the biggest advantages of a travel eSIM.
Instead of removing your UK SIM or giving up your normal number, a compatible Dual SIM phone can allow you to keep your usual line available while using a travel eSIM for mobile data abroad.
The simplest way to think about it is:
UK SIM = your usual number, calls and texts
Travel eSIM = your internet connection abroad
Just remember that Dual SIM doesn't automatically protect you from roaming charges. Check which SIM is selected for mobile data, review roaming and automatic data-switching settings, and understand what your UK provider charges at your destination.
Set it up correctly, and you can arrive abroad with your usual number still available and your travel data ready to use.
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