Posted Overseas? How to Keep Your Japanese Phone Number While You're Away

Updated: 2026-09-19

Quick answer: don't cancel the number, park it

Miya, the GetConnectedJapan guide, waving during a video call on a laptop at home. — A posting abroad doesn't have to mean starting over here — your number can come with you.

Hi, I'm Miya, and I help people get set up in Japan and stay connected to it. If you're heading overseas for a posting of a year or three and you expect to come back, the phone decision is bigger than it looks. A Japanese number isn't held in reserve for you while you're away — release it and it goes back into the pool, and you won't get that same number again. Keeping the line alive is nearly always the smaller problem to solve.

The practical shape is simple. You keep one Japanese line running on the lowest data tier, you let a local SIM carry your everyday data abroad, and your Japanese number quietly keeps doing the one job nothing else can do: receiving the codes and calls that prove to Japanese banks, apps and offices that you're you. There's one condition — the line has to be set up while you're still here.

The number is the part you can't re-buy

Think about what is attached to your number rather than to you. Your bank sends its one-time codes there. Government and My Number portals verify logins there. Your messaging account, your card company, your insurer, your delivery accounts, your management company and your utilities all hold it as the way to reach you. None of that follows you automatically when you move.

Let the number go and come back two years later with a new one, and you're not changing a digit — you're re-registering each of those relationships one at a time, some at a counter, some with documents you no longer have to hand. Keeping the line turns that whole problem into a fixed monthly amount and no lost afternoons.

What a Japanese line can still do from overseas

This is where keeping it stops being purely defensive. The Rakuten SAIKYO Plan includes international roaming in more than 100 countries and regions, with up to 2GB of high-speed data a month counted inside your plan allowance and no separate application to make. Past 2GB roaming keeps working at a reduced speed, and you can add high-speed data if you want more.

For the things that matter most while you're away, receiving SMS overseas is free — which is exactly what your two-factor codes rely on. And through the Rakuten Link app, calls from overseas to Japanese phone numbers are free, so ringing your bank, your ward office or your family back here doesn't turn into an international call bill. Some numbers sit outside the free-call scope, toll-free 0120 numbers can't be reached from abroad, and the data-only plan type doesn't include international calling — so check the official service pages for the current terms before you lean on it.

The one thing you have to do before you fly

Here's the detail that catches people out. You can apply from overseas, but the initial activation has to be completed in Japan, and SIM cards are not shipped abroad. Rakuten Link wants its first setup done here too: the official notes ask you to connect to the Rakuten network in Japan and activate Link before you travel, because authentication may not go through in some roaming areas.

So the order is unglamorous but firm — sort the line out weeks before departure, not in the departure lounge. While you're still in Japan, place one real call through Link and send yourself an SMS. Know that the thing you're about to depend on actually works before you're eight time zones away from any counter.

Abroad: local SIM for daily life, Japanese line for identity

Once you land, the comfortable setup for most people on a posting is two lines in one phone: a local SIM or eSIM for everyday data, maps and local calls, and your Japanese line kept active alongside it for SMS codes and calls home. Almost every recent phone can hold both, and which one carries data is just a setting.

That split also respects what roaming is for. The official usage notes say service may be restricted where communication runs continuously over extended periods, or where the usage pattern sits far outside normal use — so roaming is best held as your bridge and your safety net, not as your entire connection for three years. Local data for daily life, Japanese line for identity. That division has held up well for everyone I've helped.

Keep the admin quietly tidy while you're away

A few small things stop the line tripping over itself. Check that the payment method on the account won't expire partway through the posting. Check that the contact email on file is one you'll still be reading from abroad. Keep the app you manage the line through installed and logged in, because your usage, billing and settings all live there.

If your registered address or residence situation changes because of the move, don't guess at what the contract needs — ask the carrier's official support before you leave, while you can still walk into a shop. The immigration side is separate again: your re-entry permit and period of stay run on their own rules and their own deadlines, and your phone contract knows nothing about them.

Coming home, to a number that's still yours

When you fly back — for a two-week visit or for good — the line simply returns to the network here. No re-application, no new number to hand round, no week of re-verifying accounts before you can pay for things. Your bank recognises you, your codes arrive, your messaging account is where you left it.

That's the whole argument, really. Your number is the thread that stitches a Japanese life together, and a posting abroad is a pause in it rather than an ending.

Setting the line up before you go

If you don't have a Japanese line yet and the posting is already on the calendar, do this one first, because it only works from inside Japan. You apply online with your residence card or other accepted ID, and on an eSIM-capable phone the line can be live the same day — often within about fifteen minutes.

Have a look at our setup guide for eligibility and the step-by-step, and confirm the current plan and international-service terms on the official pages before you apply. Get the line settled while you're still here, and the rest of your move gets to be about the move. I'll be right here.