How it works
Your usual SIM and a travel eSIM at once: how to set it up
A compatible phone runs both lines switched on. What to pick for each, how it looks on screen, and the usual mistakes when setting it up.
Dani Requena 7 min Photo by Green Liu on Unsplash The idea to be clear about is a simple one: the travel eSIM is ADDED to your line, it doesn't replace it. Your phone ends up with two lines switched on and you decide what each one does.
What having two active lines means
It means your phone is registered on two networks at once and can receive on both. Two signal indicators appear in the status bar, and in your settings you can choose separately which line carries data, which line calls and which line sends messages.
Nothing needs restarting and no card comes out. You change it from your settings as often as you like.
The setup we recommend for travelling
| Setting | Set it to | Why |
|---|---|---|
| Mobile data | The travel eSIM | That's the line paying for browsing |
| Default calls | Your everyday line | So people still reach you on your number |
| Default messages | Your everyday line | That's where bank codes arrive |
| Data roaming | On for the eSIM only | This is what prevents surprise bills |
That last point is what really matters. With data roaming off on your everyday line, no app can go out through it even if it tries in the background.
Where each thing lives
On iPhone
In Settings, inside Mobile Data (or Cellular, depending on the version), both lines appear with a name each. That's where you pick the data line and the default voice line, and where you go into each one to switch its roaming on or off.
It's worth naming them: calling one Home and the other Travel prevents nearly every setup mistake.
On Android
In Settings, under Connections or Network & internet, inside the SIM or SIM cards section. The options are named much the same: preferred SIM for data, for calls and for messages, and roaming is switched on inside each line.
The exact spot varies between manufacturers and skins, but all three settings exist on every one of them.
What it looks like when it's right
At your destination, the status bar shows two lines: one with signal and data, which is the eSIM, and one with signal but no data, which is yours. That's exactly what you're after.
If you see the data indicator over your everyday line, something is set wrong and it's worth sorting out before you carry on.
The four usual mistakes
- Leaving data roaming on for both lines. Your phone can use yours in the background.
- Setting the eSIM as the calling line. Your number stops being the one that shows, and people trying to reach you may not get through.
- Switching your everyday line off entirely to save money. You lose your bank's texts and your calls.
- Deleting the previous eSIM before checking the new one works. A deleted profile doesn't come back on its own.
How many eSIMs fit
The chip stores several profiles, usually between five and ten, and you switch them on and off in your settings. What's limited is how many can be ACTIVE at once, which on most phones is two lines in total.
So you can keep an eSIM from a previous trip without it getting in the way or using anything, and switch it back on if you return to the same country and it's still valid.
Frequently asked questions
Can I have my usual SIM and an eSIM active at the same time?
Yes. Compatible phones take two active lines at once, one physical and one eSIM, or two eSIMs on models that allow it.
Which line do I use for what?
Data on the travel eSIM, calls and messages on your everyday line, and data roaming switched on for the eSIM only.
How do I know which line my data is going through?
Both lines appear in the status bar and only one carries the data indicator. You choose which in your mobile data settings.
How many eSIMs can I store on my phone?
Usually between five and ten stored profiles, though only two lines can be active at once on most handsets.
Can I change the setup during my trip?
Yes, as often as you like and from those same settings. None of it is permanent.
