Last updated: July 29, 2026
When you start getting ready for a trip abroad, a couple of questions tend to come up: “Can I just leave my home SIM in the phone?” and “Will it quietly connect and rack up roaming charges without me noticing?” This guide walks through the phone settings worth sorting out when you keep your regular line from home active and add a travel eSIM alongside it, split into what to do before you leave and what to do once you land. There are really only three things to do: turn off data roaming on your home line, set your travel eSIM as the line used for data, and turn off automatic line switching.
- You can leave your home line in the phone
- Only three settings need changing before departure
- Where to find them on iPhone vs. Android
- What happens to calls and SMS to your home-country number
- What to check first if you can't get online abroad
If you'd like the bigger picture on using your phone abroad first, see How to Use Your Phone Abroad: A Beginner-Friendly Guide to Travel eSIMs. This article zooms in on the part people most often trip over: how to configure things when two lines are active in the same phone.
The short answer: the only real decision is what to do with your home line
Once you add a travel eSIM, your phone holds two lines: your regular line from home and the travel eSIM. It looks confusing, but there's only one decision to make — keep the home line switched on, or turn it off for the trip. For most travelers, the easiest setup is to leave the home line on and simply turn off data roaming for that line. You don't have to cut off your home number entirely, and all of your actual internet use runs through the eSIM.
| Home line status | Calls & SMS to your home number | Internet abroad | Things to watch |
|---|---|---|---|
| Home line on + data roaming off | May still come through (depends on your plan) | Handled by the travel eSIM | Check with your home operator before you go on what incoming calls and international roaming actually cost |
| Home line switched off entirely | Not received | Handled by the travel eSIM | Least chance of unexpected charges, but don't forget to switch the line back on when you get home |
| Home line on + data roaming on | May still come through | Your home line may also use data abroad | Background app updates alone can trigger roaming data, so leave roaming off unless you specifically need it |
Roaming rates and conditions vary by operator, plan and destination, and they change over time. For anything involving money, confirm the current terms with your mobile carrier at home before you travel.
Three steps before you leave (the logic is the same on iPhone and Android)
Work through them in order and you'll be done in about ten minutes.
- Install the travel eSIM while you're still at home: with Bloomy eSIM, you tap the setup link you receive and follow the on-screen prompts to add the line. Installing it doesn't mean you start using it — you can leave the line switched off until you arrive (check the activation guidance for your specific plan).
- Turn off data roaming on your home line: this is the key setting that prevents the “I didn't realize my home line was connecting” scenario.
- Set the travel eSIM as your data line and turn off automatic switching: this keeps the choice of line in your hands rather than the phone's.
Install the eSIM somewhere with a stable connection. You can also review the full walkthrough on our setup guide.
Setting it up on iPhone
iPhone lets you configure each line separately, so you'll set options for the home line and the eSIM independently. Wording differs slightly between iOS versions.
1. Turn off data roaming per line
Go to Settings → Cellular (Mobile Data), tap your home line in the list, and switch off “Data Roaming.” Your home line will no longer connect to local networks abroad on its own.
2. Set the travel eSIM as your data line
Go to Settings → Cellular → Cellular Data and select the travel eSIM. Whichever line you pick here is the one used for internet access.
3. Turn off “Allow Cellular Data Switching”
On the same screen, switching off “Allow Cellular Data Switching” stops the phone from falling back to the other line when signal fluctuates. If you want to avoid unintended roaming, leaving this off gives you peace of mind.
4. About the default voice line
“Default Voice Line” decides which number is used when you place a call. If you still want to receive calls on your home-country number, leave it set to your home line. If you'd rather not receive them at all, you can simply switch that line off.
Setting it up on Android
Menu names vary by manufacturer and model on Android, but the logic is identical. In most cases you'll find things under Settings → Network & internet → SIMs, then configure each line.
| What you want to do | Where it is on iPhone | Where it is on Android (typical) |
|---|---|---|
| Turn a line on or off | Settings → Cellular → select line → “Turn On This Line” | Settings → Network & internet → SIMs → select SIM → “Use SIM” |
| Toggle data roaming | Settings → Cellular → select line → Data Roaming | “Roaming” inside that SIM's settings |
| Choose the line used for data | Settings → Cellular → Cellular Data | “Mobile data” on the SIMs screen |
| Stop automatic line switching | Turn off “Allow Cellular Data Switching” | Not available on some models |
If you can't find an option, try typing “roaming” or “SIM” into the search box inside the Settings app — it usually surfaces the right screen. It's also worth confirming your phone supports eSIM in advance on our eSIM-compatible devices page.
What happens to calls and SMS on your home-country number?
This is worth understanding before you go. Bloomy eSIM, like most travel eSIMs, is data-only: there's no phone number, no voice calling and no SMS. App-based calls that run over data — WhatsApp, Messenger, FaceTime and similar — work as usual. If you mostly keep in touch through messaging apps, you'll rarely notice the difference.
If you do want to receive calls or texts sent to your home-country number, you'll need to leave that line switched on. Whether incoming calls and SMS actually work abroad — and what they cost — depends on your plan, your destination and local network conditions.
Whether SMS verification codes from your bank back home, your credit card issuer or other services will reach you abroad depends on the provider and the country you're in. Don't guess — check with your home operator and with the services you rely on before you leave. Switching those accounts to an app-based authenticator ahead of time is another option worth considering.
What to do once you land
At the airport, working through these in order keeps things simple.
- Turn off airplane mode
- In Settings, switch on the travel eSIM line
- Following your eSIM's instructions, turn data roaming on for that line
- Open any web page in your browser to confirm you're connected
Step three throws a lot of people. Because a travel eSIM connects through partner networks in the country you're visiting, the instructions often tell you to switch data roaming on for the eSIM line. The easiest way to remember it: roaming stays off on your home line only. Always follow the specific guidance that comes with your plan.
If you can't get online
When data doesn't start flowing straight away, it's usually a settings detail. Try these in order.
- Turn airplane mode on, wait about ten seconds, then turn it off
- Restart the phone
- Confirm the travel eSIM is the line selected for mobile data
- Confirm data roaming is on for the eSIM line
- Set network selection to automatic, or manually re-select a local network
- Check that your plan's start date and validity period have begun
Right after landing, it can take a few minutes to latch onto a local network. Speeds and coverage also vary with the local network, your device and where exactly you are. If nothing helps, our troubleshooting page covers what to do situation by situation.
Who this setup suits — and who it doesn't
A good fit if you…
- Want to keep your home-country number active while keeping data costs abroad low
- Mostly communicate through messaging and app-based calls such as WhatsApp
- Are traveling for a few days to a few weeks and don't want to hunt for a local SIM on arrival
Consider other options if you…
- Frequently need to take voice calls made to your home-country number while abroad
- Need a local phone number for calls and SMS (look at a local SIM or a plan that includes a number)
- Have a phone that doesn't support eSIM (check the compatibility page first)
How to choose a plan for your destination
Narrow it down in this order: (1) the country or region you're visiting, (2) how many days you'll be there, (3) roughly how much data you'll use per day. If you mainly use maps, social media and translation apps, a smaller allowance goes a long way; if you plan on streaming or long video calls, give yourself more headroom. It's also worth knowing in advance how to top up if you run short. Note that plans are subject to a fair use policy, so check the terms alongside the allowance.
You can compare data allowances, durations and prices by destination on our eSIM comparison page. Available plans and terms differ by country and region, and pricing (shown in USD) can change — always confirm the current details at the time of purchase. Our FAQ covers common questions about buying and setting up a plan.
Summary
If you keep your home SIM in the phone and add a travel eSIM, there are three settings to change before departure: turn off data roaming on the home line, set the eSIM as your data line, and turn off automatic switching. On arrival, switch the eSIM line on and — following its instructions — turn roaming on for that line, and you're connected. Deciding in advance whether you actually need calls and SMS on your home-country number saves you from having to figure it out at the airport. Once you're set, compare plans by destination and trip length and pick the one that fits.
This article describes general setup steps as of July 2026. Menu names and locations vary by operating system version and device model. Terms, pricing and roaming conditions from your home operator can change, so check their official information for the latest details. Bloomy eSIM plans are data-only (no phone number, SMS or voice calls) and subject to a fair use policy; speeds and coverage depend on local partner networks, your device and your location. Plan contents and supported destinations are also subject to change.
