Dual-SIM settings for travel, line by line
A phone with a travel eSIM has two lines: your home line, with your number, and the travel eSIM, with your data. Each setting decides which line does which job. Set them once before you fly and you get local data, your own number for SMS codes, and no surprise data charges from your carrier.
The target setup
| Job | Line |
|---|---|
| Mobile data | Travel eSIM |
| Data Roaming | On for the travel eSIM, off for the home line |
| Default voice line (calls and SMS you start) | Home line |
| Cellular data switching | Off |
| iMessage, FaceTime, WhatsApp | Your number, data over the eSIM |
Step 0: label the lines
During install, iPhone asks you to label the new line. Pick "Travel", and rename your existing line "Home" if it isn't already clear. Later you can change labels under Settings → Cellular → tap the line → Cellular Plan Label. On Android, most phones let you rename a SIM from the SIMs menu. Clear names stop you from setting the wrong line.
iPhone
Everything is in Settings → Cellular (called Mobile Data in some regions).
- Cellular Data → choose Travel.
- Below that, turn Allow Cellular Data Switching off. When it's on, iPhone can move data to the home line if the eSIM signal drops, which your carrier may bill as roaming.
- Default Voice Line → choose Home. Normal calls and SMS you start go out from your own number.
- Tap Travel → Data Roaming on.
- Tap Home → Data Roaming off. Calls and SMS still work; data doesn't. Why the two lines need opposite settings is in data roaming settings, explained.
iPhone may remember which line you last used with each contact. Before calling someone, glance at the line shown on the call screen.
Android
Menu names vary by maker and Android version.
- Pixel and many others: Settings → Network & internet → SIMs. Set Mobile data to Travel, Calls preference and SMS preference to Home. Open each SIM to set Roaming.
- Samsung: Settings → Connections → SIM manager. Under preferred SIMs, set Calls and Messages to Home and Mobile data to Travel. Turn off any automatic data switching option there. Data roaming is under Connections → Mobile networks.
If you can't find a setting, search the Settings app for "roaming" or "mobile data".
Why each choice matters
Mobile data on the eSIM
The eSIM is the plan you paid for. If mobile data points at the home line, the eSIM sits unused and your carrier's roaming rules decide what you pay.
Data switching off
Automatic switching is useful at home with two domestic lines. Abroad, it can move you onto the line that costs money at the moment the eSIM's signal is weak, such as on a train or in a basement.
Home line kept on
Your bank, airline and many apps send codes by SMS to your number. Keeping the home line on means those codes still arrive. Receiving calls and SMS abroad may cost something depending on your carrier, so check its roaming rates.
Default voice line on Home
Most travel eSIMs are data-only and have no number to call from. If yours includes a local number and minutes, you can choose it for local calls instead.
Messaging apps and your number
iMessage and FaceTime stay tied to your number while their data flows over the eSIM. WhatsApp keeps your account and number too, because it's linked to the number, not the line carrying data. The details, including what to avoid, are in keeping your WhatsApp number abroad.
Two alternative setups
- Quiet home line. Turn the home line off completely (iPhone: tap Home → Turn On This Line). No calls, no SMS, no charges. Good for a digital detox; bad if you need bank codes.
- Two data plans. If you're crossing from one plan's country into another's, switch Cellular Data to the plan that covers where you are, and keep roaming on for both eSIMs. One eSIM for a multi-country trip covers when that is worth it.
Back home
Set mobile data back to Home and turn data switching back on if you used it before. Whether to keep or delete the travel eSIM is covered in delete or keep your eSIM after the trip. If you land and get signal but no data, work through the landing-day fix sequence. Install steps are in our iPhone and Android guides. To get a plan for your trip, pick a destination.
Questions
Can I use a physical SIM and an eSIM at the same time?
Yes, on any dual-SIM phone with eSIM. Keep your home SIM on for calls and SMS codes with Data Roaming off, and set the travel eSIM as the cellular data line with Data Roaming on.
Which line should be my default voice line abroad?
Usually your home line, since the travel eSIM is data-only on most plans. Calls you make from it are charged by your carrier, so use app calls over data if you want to avoid that.
Should Allow Cellular Data Switching be on?
Usually off on a trip. When on, the phone can move data to the home line when the eSIM signal is weak, and your carrier may bill you for it.
Will iMessage and FaceTime still use my number?
Yes. They keep your number while their data runs over the travel eSIM, as long as the home line stays active.
Should I turn the home line off completely?
Only if you don't need SMS codes. Turning it off stops all calls and SMS. Keeping it on with Data Roaming off is the usual setup.