Last updated: August 23, 2026
Plenty of travelers set up a destination eSIM before departure, come home, open the bill and think, "wait — what is this?" In most cases the eSIM isn't the culprit. The line you use every day at home stayed active in your phone and kept working while you were abroad. The short version: once you add a travel eSIM, check three things before you leave — turn data roaming off on your home line, set the travel eSIM as the line used for mobile data, and turn off automatic line switching. Below, we walk through the settings that most often trip people up on dual-SIM phones, following the flow on both iPhone and Android.
- Adding an eSIM doesn't switch your home line off
- Data roaming is turned off per line, not phone-wide
- Point mobile data at your travel eSIM
- Turn off automatic switching to stop unwanted connections
- Data-only still lets you make app-based calls
Why your home line keeps connecting even after you add an eSIM
The reason is simple: adding a travel eSIM doesn't remove your home-country line. It stays inside the phone as a second active line.
On a dual-SIM device, your physical SIM (or the eSIM that was already installed) and the newly added travel eSIM are both live at the same time. Even while you're browsing on the travel eSIM, an active home line will also latch onto a local operator's network. Depending on your settings, that can result in international roaming data being used on the home line.
The other thing people overlook is calls and texts. As long as your home line is active, incoming calls to your phone number and incoming SMS keep landing on that line. How incoming calls are charged, and how forwarding is handled, depends on your plan — so it's worth checking your home operator's current terms before you go.
If you'd like to understand why phone bills spike abroad in the first place, read Using your phone abroad as-is: how bills get so high, and the settings that prevent it alongside this article. The settings here make a lot more sense with that background.
The three settings to review before departure
Here are the three items to confirm. Each takes a couple of minutes.
| Setting to check | What it's for | Set it to |
|---|---|---|
| Data roaming on your home line | Stops your home line from using data abroad on its own | Off |
| Line used for mobile data | Routes your data through the travel eSIM | Select the eSIM |
| Automatic line switching | Prevents the phone falling back to the home line when signal fluctuates | Off |
The key point: data roaming is a per-line setting, not a phone-wide one. Turning it off for your home line leaves the travel eSIM's own setting untouched.
On iPhone
Open Settings → Cellular (Mobile Data) and you'll see a list of your lines. Select your home-country line and switch Data Roaming off. Go back to the list, choose your travel eSIM under "Cellular Data," and on that same screen turn off "Allow Cellular Data Switching."
On Android
Go to Settings → Network & internet → SIMs (called "Mobile network" on some models), pick your home line, and turn Roaming off. Then set the travel eSIM as the line used for mobile data. Menu names and their order vary by manufacturer and OS version, so if you can't find the option, type "roaming" into the search box at the top of Settings.
While you switch roaming off on your home line, the travel eSIM may actually need data roaming switched on. Travel eSIMs often connect to local operators on a roaming basis. Which way it should be set is stated in the instructions for the plan you bought, so follow those.
Airplane mode alone isn't always enough
Airplane mode is an easy way to cut everything off for a moment, but it's a poor fit for day-to-day use on a trip.
It stops all connections at once — but the moment you want to get online with your travel eSIM, you have to turn it off, and your home line comes back with it. You can leave airplane mode on and enable Wi-Fi only, but unless the per-line settings are sorted out, the same worry returns the second you need mobile data. Getting this done before you leave means you're not fiddling with settings during those hectic first hours after landing.
Know what you'll stop receiving before you change anything
Sorting out what still reaches you and what doesn't makes the decision much easier.
| Approach | Mobile data | Calls & SMS to your number |
|---|---|---|
| Data roaming off on the home line only | Should not be used on the home line | Still received (charges depend on your plan) |
| Home line turned off entirely | Not used | Not received |
| Travel eSIM (data-only) | Available within the plan's data allowance | Not supported — no calls or SMS to a phone number |
Bloomy eSIM, like most travel eSIMs, is data-only. "Data-only" sounds like you can't call anyone, but app-based calling over data — WhatsApp, Messenger, FaceTime and similar — works as usual. What you don't get is calling and texting via your phone number (voice calls and SMS). If you already keep in touch with family and friends mostly through apps, day-to-day use will feel much the same as at home.
Do take care, though, if you need to receive SMS verification codes from your bank back home or other services while abroad. Whether SMS reaches you overseas, and what it costs, depends on your contract and where you're travelling. Check your operator's official information before departure, and decide your approach in advance — that might mean leaving the home line active, or arranging another way to receive codes. We cover phone-number and SMS questions further in our articles on phone numbers and SMS.
Who needs to do this — and who doesn't
If you're travelling with your home-country line still under contract, it's worth opening the settings screen at least once.
Worth reviewing if you…
- Travel with a dual-SIM phone and keep your home line active
- Are setting up phones for family members or children too (each device needs its own settings)
- Are staying a while — study abroad, a work posting — where usage adds up
- Rarely open the settings app and run your phone on its defaults
Less of a concern if you…
- Are travelling with the home SIM removed, or with a separate phone kept for trips
- Have suspended or cancelled your home line for the duration
That said, contracts and device settings differ from person to person. Even if you think you're in the clear, opening the settings screen once before departure and seeing the current state with your own eyes saves you carrying the worry with you.
What to check, in order, when you can't get online
After changing several settings, it's easy to lose track of what to undo when the connection doesn't work. Working through this order makes it easier to isolate the cause.
- Turn airplane mode on, wait a few seconds, then turn it off
- Confirm the travel eSIM line is switched on
- Confirm the line used for mobile data is the travel eSIM
- Confirm data roaming on the travel eSIM matches what the plan's instructions say
- Restart the device
- If it still won't connect, check manual network selection and the APN settings
Step-by-step instructions are collected on our troubleshooting page. Most issues clear up somewhere in steps 1–3. Resist the urge to change several settings at once — one at a time keeps the cause visible.
How it works with Bloomy eSIM
With Bloomy eSIM, you tap the setup link you receive after purchase and follow the on-screen prompts to add the line. When you arrive, switch that line on and you're connected. Adding it doesn't change anything about your home line, which is exactly why the three checks in this article are best done before you leave.
Bloomy eSIM plans are data-only — no phone number, no SMS, no voice calls — and are subject to a fair use policy. Actual speeds and coverage vary with the local network, your device and where you are.
Want to see the steps first? Head to the setup guide, and check the FAQ for pre-purchase questions.
Already know where you're headed? Browse the eSIM comparison page to find a plan by country or region, data allowance and number of days. Pricing and plan details can change, so please confirm the current information shown at the time of purchase.
In summary: a few minutes before departure, fewer surprises after
Adding a travel eSIM doesn't stop your home-country line — it keeps running inside your phone. That's why it matters to confirm three things before you go: data roaming off on the home line, mobile data pointed at the eSIM, and automatic switching off. Knowing in advance how switching off the home line changes incoming calls and SMS means one less thing to panic about mid-trip.
As a next step, open the settings on your own phone and see how many lines are currently active. Then check the comparison page for a plan that suits your destination, and your preparation is done in one sitting.
This article is based on information available as of August 2026. The names of settings vary by OS version and device model, and roaming charges, roaming conditions and SMS handling depend on your own mobile operator. For the latest details, please check with your operator and on the official Bloomy eSIM pages.
