Yes, you can keep your home number active while using a Laos eSIM for data. Your phone runs both at once. Calls and texts stay on your home line, data comes from the Laos eSIM, and you pay nothing to your home carrier as long as you set it up properly.
That last part is where people get caught out. The setup takes about two minutes, and getting one toggle wrong is the difference between a normal bill and a roaming charge you will remember.
What dual SIM actually means on a modern phone
Your phone can hold two active lines: your usual physical SIM, and an eSIM installed digitally. Both register with their networks at the same time. Both can receive calls and messages.
What your phone will not do is use both for data simultaneously. One line is the data line, and you choose which. That is the entire configuration.
So the arrangement that works for almost every traveller is:
| Line | Used for | Data roaming |
|---|---|---|
| Home SIM | Calls and SMS only. Bank codes, two-factor authentication, anyone ringing your usual number. | Off |
| Laos eSIM | All mobile data. Maps, messaging apps, everything. | On |
Your home number keeps working for the things that need it. Your data costs what a local plan costs instead of what international roaming costs.
The one setting that matters most
Turn data roaming OFF on your home line.
If you leave it on, your home SIM will quietly use the Lao network for background data whenever it feels like it. Operating system updates, cloud photo sync, email checking in the background. You will not notice until the bill arrives.
Turning it off does not affect calls or texts on that line. Those still work. It only stops the data.
Do this before you fly, not after you land.
Setting it up on iPhone
Install your Laos eSIM first, then work through this. If you have not installed it yet, or the QR code will not scan, see our eSIM troubleshooting guide.
1. Label your lines
Go to Settings > Cellular. You will see both lines listed. Tap each one and give it a name you will recognise, such as Home and Laos. iPhone offers preset labels like Primary and Travel, or you can type a custom one.
This sounds cosmetic. It is not. Every screen after this asks you to choose between two lines, and “Primary” and “Secondary” are much easier to mix up than “Home” and “Laos”.
2. Turn off data roaming on your home line
Settings > Cellular > tap your home line > turn Data Roaming off.
3. Turn on data roaming for the Laos eSIM
Settings > Cellular > tap your Laos line > turn Data Roaming on.
This one confuses people every time. Your eSIM is a Lao line and you are in Laos, so why is it roaming? Because your iPhone classifies any line that is not your home carrier as roaming, regardless of geography. Leave this off and the eSIM will not pass data at all.
4. Set the Laos eSIM as your data line
Settings > Cellular > Cellular Data > select your Laos line.
5. Turn off “Allow Cellular Data Switching”
On the same Cellular Data screen there is a toggle called Allow Cellular Data Switching. Turn it off.
Left on, your iPhone will fall back to your home line for data whenever it thinks the Laos line is struggling. That is a helpful feature at home and an expensive one abroad.
6. Choose your default voice line
Settings > Cellular > Default Voice Line > select your home line.
Outgoing calls will use your home number by default, which is what you want for anything official. You can still pick the other line manually when dialling.
7. Point iMessage and FaceTime at the right line
Settings > Messages > Send & Receive and Settings > FaceTime. Confirm your home number is selected. If your eSIM line gets selected, people messaging your usual number may not reach you.
Setting it up on Android
Menu names vary by manufacturer. The path is broadly the same.
Stock Android and Pixel
- Go to Settings > Network & internet > SIMs
- Select your home SIM, turn Roaming off
- Select your Laos eSIM, turn Roaming on
- Back on the SIMs screen, find Mobile data and select the Laos eSIM
- Find Calls and select your home SIM
- Find SMS and select your home SIM
- Rename each SIM to something obvious while you are in there
Samsung
- Go to Settings > Connections > SIM manager
- Under Preferred SIM, set Calls and Text messages to your home SIM
- Set Mobile data to your Laos eSIM
- Turn off Dual SIM always on only if you want to save battery. Leaving it on keeps both lines reachable.
- Go to Settings > Connections > Mobile networks, select each SIM and set Data roaming individually: off for home, on for Laos
Xiaomi, OPPO, OnePlus and others
Look for Settings > SIM cards & mobile networks or Settings > Mobile network. The same four settings exist: data roaming per SIM, default data SIM, default call SIM, default SMS SIM. Set them the same way.
What still works on your home number
Everything that does not need data.
Incoming calls ring normally. Incoming SMS arrives normally, which matters because that is how most banks and services send verification codes. Outgoing calls and texts work, though your home carrier will charge international rates for making them.
What will not arrive is anything that needs data on that line. WhatsApp messages, for instance, come in over data, so they will arrive over your Laos eSIM connection regardless of which number the account is tied to. That is fine and it is how it should work.
Common mistakes
Leaving data roaming on for the home line
The expensive one. Background sync on your home line at international roaming rates. Check this twice.
Turning off the home line entirely
Some people disable the home SIM to be safe. Then their bank sends a verification code by SMS and it never arrives. Keep the line active with data roaming off. That is the safe configuration, not switching it off.
Forgetting to set the data line
Installing an eSIM does not make it your data line. If you skip that step your phone carries on using the home SIM, and you are paying roaming rates while a perfectly good local plan sits unused.
Assuming airplane mode plus Wi-Fi is equivalent
It is not, and you lose SMS delivery. Dual SIM configured properly is better in every respect.
Not testing before departure
Install the eSIM at home. It will sit inactive until you land in Laos, which is normal, but you will have confirmed it installed cleanly and you can label your lines and set your toggles in advance. Sorting this out on hotel Wi-Fi after landing is worse than doing it on your own sofa.
Battery life
Running two lines uses slightly more battery, since the phone maintains two network registrations. On a modern handset the difference is small, generally in the range of a few percent over a day.
If you are on a long travel day with no charger, you can turn off the home line temporarily and switch it back on when you need it. Just remember that verification codes will not arrive while it is off.
Which phones support this
Any phone with eSIM support can run dual SIM this way. In practice that means iPhone XR, XS or later, Google Pixel 3 or later, Samsung Galaxy S20 or later and most flagships since, plus a growing number of mid-range Android phones.
Two things to check before you rely on it. Some phones sold in mainland China and Hong Kong ship without eSIM hardware even where the same model has it elsewhere. And a carrier-locked handset will often hide eSIM settings entirely, even on a model that supports it.
If your phone does not offer an eSIM option at all, our troubleshooting guide covers what to check.
Get set up before you fly
Our Laos eSIMs arrive by email, install in a couple of minutes, and activate by themselves when you land and connect to the network. No code to dial, no queue at the airport, no handing over your passport at a SIM counter.
Install at home, set the toggles above, and you are online the moment you step off the plane with your home number still ringing.
Frequently asked questions
Can I keep my home number while using a Laos eSIM?
Yes. Both lines stay active. Your home number handles calls and SMS, the Laos eSIM handles data.
Will I be charged roaming on my home line?
Not for data, provided you turn data roaming off on that line. Incoming calls and texts may still incur charges depending on your home carrier’s terms, so check their international rates.
Will I still receive bank verification codes?
Yes, as long as you leave your home line switched on. SMS delivery does not need data. This is the main reason to keep the line active rather than disabling it.
Can I use both lines for data at the same time?
No. Phones register both lines but use only one for data. You choose which.
Do I need to turn on data roaming for the Laos eSIM?
Yes. Your phone treats any non-home line as roaming even while you are in the country. Without it the eSIM will not pass data.
What happens to WhatsApp?
It stays tied to your home number and works over whichever data connection is active, which will be your Laos eSIM. Nothing to change.
Should I turn off my home SIM to be safe?
No. Leave it on with data roaming off. Switching it off entirely means missing verification codes and calls.
