Data only SIM card for travel: what it costs, and how to keep your number

What is a data only SIM card?

A data only SIM card gives you mobile internet and nothing else: no phone number, no calls, no texts. For travel that's usually all you need, because the calls and messages you actually make go through WhatsApp, FaceTime or LINE over data anyway.

You've probably already met one without knowing. Most of the travel eSIMs on this site are data only. Airalo says many of its eSIMs are data only, and its plan details tell you which: "Data Only" against "Data, Voice & Text". Holafly's day-based eSIMs are data only; only its monthly and annual Unlimited Plans come with a number, and that number receives texts but doesn't take normal calls. More on both in Airalo phone number and Holafly phone number.

Prices below come from our own country guides and are checkout readings from 13 to 18 August 2026, in US dollars.

A local data SIM, or a travel eSIM?

Two very different things get called a data SIM abroad.

The first is a local prepaid SIM sold as data only. Japan is the clearest case: every tourist SIM sold there is data only, whatever counter you buy it at, for about $12 at the airport, with a passport scan every time. The 24-hour vending machines at Narita, Haneda and Kansai sell the same thing. Plenty of other countries' tourist SIMs come with a local number you'll never use, like Turkcell's Istanbul Airport pack with 200 minutes, so data only is more a description of how you'll use it than of what's on sale.

The second is a travel eSIM, bought before you fly. No counter, no passport, and the cost per gigabyte falls sharply as the plan grows.

That last row is the trap. Small plans look cheap and are the worst value anyone sells. Our cheapest eSIM table ranks every country by cost per gigabyte; the median is $0.98.

Where the local SIM wins, it wins clearly. Italy's Iliad sells €9.99 a month for 120 GB plus calls from mall kiosks, and an Indian bundle works out near 20 cents a gigabyte if you can face the passport, visa and photo. Mexico is the easy one: a Telcel SIM from any Oxxo for about MXN 99, roughly $6, with no ID and no registration, and our Mexico guide reckons an eSIM isn't meaningfully cheaper, and is probably dearer for larger amounts of data. For a week, the eSIM is usually simpler and often cheaper. For a month in one country, check the local option first.

Prepaid SIM card with unlimited data: what you actually get

"Unlimited" on a travel eSIM means you won't run out. It doesn't mean full speed all day.

Airalo slows you to 1 Mbps after 3 GB in a day by default. Nomad drops you to 512 kbps after 2 GB. Holafly publishes no figure, saying only that some operators may reduce speed after a high-speed limit, for up to a day. So the most fast data a week of Airalo unlimited can give you is 21 GB, and a week of Nomad's is 14 GB.

For short, heavy trips the price is reasonable. Nomad charges $11 for three days in thirteen European countries; a week in Japan is $25 on Nomad, $27 on Airalo and $27.50 on Holafly. A week in the USA on Airalo is $25.

For a month it rarely makes sense. Airalo's Japan unlimited month is $69, while Nomad's metered 50 GB month is $35. In Spain, Airalo's 50 GB is $39 against $63 unlimited. Most people never get near 50 GB. If you're looking for a cheap SIM card with unlimited data for a long stay, the cheap part and the unlimited part pull in opposite directions; our unlimited data eSIM guide has the full tables.

How to keep WhatsApp and your home number

This is the bit people worry about, and it's simpler than it looks. On a phone with eSIM you keep both lines: your home SIM for calls and texts, the data only eSIM for data.

Apple's travel guidance says that with both lines on, your primary line keeps working, and you can carry on using FaceTime, iMessage and other VoIP apps. Choose the data line under Settings > Cellular > Cellular Data. On a Pixel it's Settings > Network & internet > SIMs, where you set separate SIMs for calls, texts and mobile data; only one can carry data at a time.

WhatsApp keeps your home number as your identity because the account was registered to it, not because the SIM is doing the work. It runs over whichever data connection you give it. Your bank's text-message codes, though, still arrive through the home line, which is the real reason to leave it switched on.

One caution from Apple's page: you might still incur roaming fees from your home line. Turn off data roaming on it, so the eSIM carries all your data. Calls and texts on the home line can still be billed at your carrier's roaming rates, so check those before you answer every call. Our data roaming guide shows where the switch is.

A physical local SIM in a single-SIM phone is different. The home SIM comes out, so texts to your number stop until you put it back.

Which data only SIM card would we buy?

For a trip under two weeks: a travel eSIM in the 5 to 20 GB range, bought at home, with your home line left on for texts. Check your phone on our eSIM compatible phones list first. For a month in Italy, Spain, Mexico or India: the local SIM, bought in town. For a short trip where you'll tether a laptop all day: unlimited, but read the daily cap before you pay. And in Japan, whichever you choose, install LINE.