Data Roaming: On or Off With a Travel eSIM?

With a travel eSIM, switch data roaming ON for the eSIM line — that's how the plan is designed to connect abroad — and switch it OFF for your home SIM, because the home line is the one that would bill you roaming charges. Getting this back to front is the single most common source of confusion for first-time eSIM travellers, so it's worth setting once and understanding why.

This guide gives you the rule per line, explains why "roaming on" never means a surprise bill on your eSIM, shows exactly where the toggles live on iPhone and Android, and covers the one situation where you might leave your home SIM roaming on for a few minutes.

The rule, per line

Think of your two lines as having two different jobs. The travel eSIM's job is to get you online in your destination, and it does that by connecting to local partner networks — which your phone sees as roaming. The home SIM's job is to stay reachable for calls and texts, and its data roaming is precisely the switch that racks up your carrier's international charges. So you treat them oppositely:

Line	Data Roaming	Why
Travel eSIM	ON	The plan operates as a roaming profile on local partner networks, so it needs roaming permitted to connect
Home SIM	OFF	Stops your home carrier from charging its own roaming data rates while you're abroad

That's the whole rule. Set data roaming on for the eSIM, off for the home SIM, and make sure the eSIM is chosen as your Mobile Data line. Everything else below is the reasoning and the button-by-button path.

Why roaming ON doesn't mean roaming charges

The word "roaming" does two different jobs, and that's where the fear comes from. Technically, roaming just means a line is connecting through a network that isn't its own home network — it describes the connection, not the cost. Your travel eSIM is built to do exactly that, and the price you paid already covers your usage in the plan's destination. Turning roaming on for the eSIM doesn't add a charge; it's simply the permission the plan needs to work.

The billing kind of roaming is what happens when your home SIM connects to a foreign network. That's when your home carrier applies international data rates, and that's the bill people dread. Switching the home line's data roaming off closes that door completely.

There's a second safety net worth naming: a travel eSIM is prepaid. It carries a fixed allowance and nothing more — there's no monthly account behind it to run into the red. When the data is gone, the connection stops. It cannot quietly keep spending, so even with roaming firmly on, an open-ended bill is impossible on the eSIM line.

Where the toggles live

The settings sit in slightly different places on each platform, and on a dual-SIM phone every line has its own roaming switch. Set them per line.

On iPhone:

1. Open Settings, then Mobile Data (labelled Mobile Service on some models).
2. Tap your travel eSIM in the list of lines, turn Data Roaming ON, and make sure the line is enabled.
3. Go back, tap your home SIM, and turn its Data Roaming OFF.
4. Back on the main Mobile Data screen, set Mobile Data to the travel eSIM so it handles your internet.

On Android:

1. Open Settings, then Network and internet, then SIMs.
2. Select your travel eSIM, and turn Roaming ON.
3. Return, select your home SIM, and turn Roaming OFF.
4. Under mobile data preference, choose the travel eSIM as the line for mobile data.

Menu wording shifts a little between phone models and Android versions, but the shape is always the same: pick a line, then set that line's roaming switch.

When to leave home-SIM roaming on briefly

There's one honest exception. If your bank sends security codes — one-time passwords for logging in or approving a payment — as a text to your home number, you may need the home SIM briefly reachable to receive them. Receiving a text is free or low-cost on most home carriers even abroad, but that isn't universal, so check your home carrier's roaming rates before you assume it's free, and remember that home-SIM data and calls while roaming can be expensive even when incoming texts are not.

In practice you can keep the home SIM on for calls and texts with its data roaming off, which lets an OTP text arrive without opening the door to data charges. If you'd rather not depend on SMS to your home number at all, an authenticator app or a banking app that approves logins over the eSIM's data connection sidesteps the problem entirely. Bear in mind that eSIM Today plans are data-only, so they never carry a phone number of their own to receive those texts — that job stays with your home SIM. Our guide on getting a WhatsApp number to work abroad explains how messaging and verification fit together on a data-only travel plan.

Quick pre-flight setup

Set this up over Wi-Fi before you fly, so you land already connected:

1. Install the travel eSIM at home while you're on Wi-Fi, following your phone's setup guide.
2. Turn Data Roaming ON for the eSIM line and OFF for your home SIM, as above.
3. Set the eSIM as your Mobile Data line so your internet runs through the plan, not your home carrier.
4. Leave the eSIM line's data off until you arrive if you want to be certain nothing runs before the trip, then flip it on when you land and check a web page loads.

Once you touch down, your data should connect automatically. If you're not sure how to install the profile in the first place, our step-by-step Android eSIM installation guide walks the whole process from QR code to first connection.

Ready to pick a plan for your destination? Browse eSIM Today data plans and set it up before you leave — you'll be online the moment you arrive.

FAQ

Will I get a huge bill if data roaming is on? Not from your travel eSIM. A prepaid travel plan stops the moment its allowance is used up — there's no account to run into the red and no open-ended bill. Bill shock comes from your home SIM roaming on a foreign network at your carrier's rates, which is exactly why you switch data roaming OFF for the home line while it stays ON for the eSIM.

Should I turn my home SIM off completely? You don't have to. Leaving the home SIM on with its data roaming switched OFF keeps it available for calls and texts on a dual-SIM phone while it can't quietly rack up data charges. Turn the home line fully off only if you want silence, or if you're worried about apps finding a way to use it. For most travellers, home SIM on with roaming off is the sweet spot.

Why does my eSIM only work with data roaming enabled? Travel eSIM plans typically connect to partner networks in your destination rather than a home network, and your phone treats that as roaming. Data roaming is the switch that permits a line to use a network other than its own, so the eSIM needs it ON to get online. It's a technical permission, not a billing trigger — the plan's price already covers usage in its destination.

Do I need to change these settings for every country? Usually not. Once data roaming is ON for the travel eSIM and OFF for your home SIM, the settings hold as you cross borders. A regional plan that covers several countries keeps working without changes. You'd only revisit the settings if you install a new eSIM for a different trip or switch which line handles your mobile data.

What happens when my eSIM data runs out? The connection simply stops — pages won't load and apps can't reach the internet. Because a prepaid travel plan has no billing account behind it, running out costs you nothing extra; it just goes quiet. You then top up the plan if that's supported, or buy a fresh eSIM. Check your remaining data in your account before a big travel day so it doesn't run dry at an awkward moment.