Roamclarity

What breaks when you travel on a data-only eSIM — checked country by country.

Before you land

Will a data-only eSIM be enough where you’re going?

It gets you online, but it comes with no phone number — and in Japan, apps like PayPay won’t take a foreign one. Pick a destination to see which apps turn you away and which have a way round.

Why “it works fine” and “I couldn’t sign up” are both true

What a data-only eSIM gives you

Data, and nothing else

Maps, messages, translation and browsing all run on data, and all of them work.

What sign-up screens ask for

A phone number

Some accept any number that can receive a text, so keeping your home SIM switched on is enough. Some accept only a local number — and a data-only eSIM has no number to give them.

Japan · checked 11 Sep 2026

The apps in Japan that won’t take a foreign number

Each from the company’s own published material. The full list of ten, with sources and a quick check, is on the Japan page.

PayPay

Japanese number

Japan's most-used QR payment app

PayPay's own help page states that overseas mobile numbers cannot be used and that you need a Japanese mobile number to register.

Company's own documentation PayPay help centre

d払い (d Payment)

Japanese number

NTT Docomo's payment app

Registration accepts only an 11-digit number issued in Japan. Overseas numbers are outside the scope of the service.

Company's own documentation Docomo d払い help

The way round

GO

Works on data alone

Japan's largest taxi-hailing app

GO added sign-up with overseas mobile numbers in November 2023. It also publishes a fallback for people who cannot receive an SMS at all: identity check by passport photo and a selfie, inside the same app. That fallback is what makes it usable on a data-only eSIM with no other line.

Company's own documentation GO Inc. press release, 10 Nov 2023

Every claim here is tagged with where it came from and how sure we are. When a company says it in its own help pages, we say so. When it is traveller reports, we say that too, and we do not dress it up.

Some links on country pages earn us a commission. They are marked where they appear, and they do not decide what we list or in what order.