Why do you need a Japanese phone number? 12 things that absolutely require one

Quick Answer

In Japan, a Japanese mobile phone number (starting with 090, 080, or 070) is essentially your "second form of ID": you need it to open a bank account, rent an apartment, apply for a job/part-time work, register for electricity–gas–water, receive courier deliveries, verify LINE and PayPay, book hospital appointments, and fill out administrative paperwork.

A data-only SIM (internet only) does NOT come with a Japanese phone number, so you can't receive SMS verification codes and can't call 110/119. If you're living in Japan long-term, at minimum you need a voice SIM with a 090/080/070 number; a data-only SIM should only be used as a secondary SIM or for short-term stays.

This article lists 12 real-life situations where a Japanese phone number is mandatory, along with how to prepare your documents to register for one.

Who This Article Is For

• International students, technical interns, specified skilled workers, and engineers who have just arrived in Japan and aren't sure which type of SIM to buy.
• People currently using a cheap data-only SIM but keep getting rejected when signing up for banks, PayPay, or Mercari because they "can't receive an SMS code."
• People currently using a friend's or company's phone number who want to get their own number under their own name.
• People about to change jobs, move to a new home, or apply for a credit card — procedures that always ask for a contact number.
• Anyone who wants to understand the difference between a 090/080/070 number and a 050 IP number before deciding.

Cases Where This May NOT Apply

You may not need to rush into buying a voice SIM if you fall into one of these situations:

• Short-term travel (under 90 days): you only need data for Google Maps, LINE, and translation apps. In this case, an eSIM or portable WiFi is enough.
• Your company/school has already provided a work phone with a Japanese number under your name, and you're able to use that number for all your personal procedures.
• You don't have a residence card (zairyu card) yet: under Japanese law, to register a phone number under your own name, you must present valid identification. While waiting for your card, use a data-only SIM or WiFi temporarily.
• You're returning to your home country within 1–2 months: signing a voice contract may incur an early cancellation fee, so consider a short-term plan instead.

Aside from the cases above, if you're living in Japan for 6 months or more, you'll almost certainly need a Japanese phone number.

12 Situations Where You Must Have a Japanese Phone Number

1. Opening a bank account. Yucho (Japan Post Bank), MUFG, SMBC, Rakuten Bank, PayPay Bank, and others all have a mandatory "contact phone number" field on their application forms. Online banks also send verification codes via SMS and make verification calls. Without a Japanese number, your application is often rejected right at the counter.

2. Applying for a credit card, installment payments, or buying a phone on installment. The screening department (shinsa) will call you directly or call your workplace. An unreachable phone number = failed screening.

3. Renting an apartment. Rental contracts require the tenant's phone number, and the guarantor company (hoshou gaisha) will call to verify before approving. This is a step that trips up many international students who only have a data-only SIM.

4. Applying for full-time jobs and part-time work. The rirekisho (履歴書) resume form has a phone number field. Japanese employers still commonly call to arrange interviews rather than sending messages. If you don't answer for 1–2 days, your application is often passed over.

5. Registering for electricity, gas, and water when moving. Gas in particular requires scheduling a technician visit to turn on the valve and perform a safety check — they contact you by phone. Many gas companies only accept appointment bookings through their call center.

6. Receiving courier deliveries (Yamato, Sagawa, Japan Post). When you're not home, the delivery notice slip (fuzai hyou) requires you to call or message to reschedule delivery. These companies' apps also use SMS verification sent to a Japanese number.

7. Registering for and recovering LINE. LINE is the default communication infrastructure in Japan — used by schools, companies, and dormitory management alike. LINE accounts are linked to phone numbers; if you switch devices without a number to receive SMS, you risk losing your account entirely along with all your chat groups.

8. E-wallets and cashless payments: PayPay, Rakuten Pay, d払い, au PAY. All of these require SMS verification using a Japanese mobile number. PayPay in particular is widely used at supermarkets, restaurants, and konbini — without a Japanese number, you disqualify yourself from major cashback campaigns.

9. Online shopping: Amazon Japan, Mercari, Rakuten, Yahoo! Auction. Mercari — where foreigners often buy cheap secondhand items — requires phone number verification before you can sell items and withdraw funds.

10. Booking appointments at hospitals, clinics, dental offices, and for vaccinations. Most clinics in Japan still take appointments by phone; if test results come back abnormal, they'll call you back. Registering at large hospitals also requires a contact number on your patient record.

11. Procedures at the ward office/city office and other administrative paperwork. Move-in/move-out notification forms, national health insurance registration, nenkin pension enrollment, various benefit applications, and more all have a phone number field. If your application is missing documents, staff will call you before returning it. Residence status renewal applications submitted to the Immigration Bureau also include a contact phone number field.

12. Calling emergency services 110 (police) and 119 (fire/ambulance). This is the most critical reason. A data-only SIM cannot make emergency calls. In a house fire, traffic accident, earthquake, or chest pain in the middle of the night — you can't rely on WiFi or internet calling apps.

Can a 050 Number (IP Number) Be a Substitute?

A 050 number is an internet calling number, cheap and easy to register for, but it has clear limitations:

Practical conclusion: a 050 number should only be used as a supplement, not as a replacement for a Japanese mobile number for important procedures.

Steps to Get a Japanese Phone Number

1. Check your residence card (zairyu card): make sure it has at least a few months of validity left, and that your name and address match your registration information.
2. Choose the type of number: if you only need data, buy a monthly data SIM; if you need a phone number under your own name, choose a voice SIM.
3. Choose the right data allowance: 3–5GB if you mainly use WiFi at home and school; 20GB or more if you frequently watch videos or work outside.
4. Prepare a payment method: a Japanese credit card, bank account, or bank transfer. See details on the support page.
5. Fill out the application form on the voice SIM registration page, and upload clear photos of the front and back of your residence card (sharp, no glare, no cut-off corners).
6. Wait for identity verification. Under Japan's regulations against fraudulent mobile phone use, carriers are required to verify the identity of applicants.
7. Receive and activate your SIM: physical SIMs are sent by mail; eSIMs are delivered as a QR code via email for you to scan and install.
8. Set up the APN according to the included instructions, restart your device, and make a test call to check that it works.
9. Update your new number in important accounts: LINE, bank, PayPay, workplace, school, and the Immigration Bureau (if your application is still being processed).

If you already have a Japanese number and only want to switch carriers while keeping the same number, ask your current carrier for an MNP code (number portability code) before registering with the new carrier.

Documents You Need to Prepare

• Residence card (在留カード) that's still valid — mandatory, photograph both sides.
• Passport — some carriers require this in addition, especially if your name on the residence card is abbreviated.
• Address in Japan for SIM delivery — write the room number in full, and the name on your mailbox must match the recipient's name, otherwise the post office will return the package.
• A working email address — used to receive the eSIM code and contract notifications.
• Credit card or bank account information for monthly payments.
• A carrier-unlocked (SIM-free) phone — phones bought on installment overseas or locked to a Japanese carrier may not accept a new SIM.

Note: a My Number card isn't required by every carrier, but having one on hand can speed up the process in many cases. Never hand over the original of your residence card or My Number card to a stranger who offers to "register on your behalf."

Reference Costs

These are general market reference prices, not an official quote. Prices and promotions change over time — please check current pricing on the products page.

Money-saving tip: if you have WiFi available at home or your dorm, choose a voice + low data plan (3–5GB) instead of a large data plan. If you'll be in Japan for a full 12 months, a 12-month prepaid SIM plan is usually cheaper than paying month by month.

Processing Time

• eSIM: usually the fastest, you can receive the QR code within the same business day after your application is approved.
• Physical SIM: application approval takes 1–2 business days, plus 1–3 days for mail delivery depending on your area (Hokkaido, Okinawa, and remote areas may take longer).
• Number portability (MNP): getting the MNP code takes anywhere from a few minutes to 1 day; once the new SIM is activated, the old number stops working almost immediately.
• Missing documents/blurry photos: add 1–3 days for each resubmission. This is the most common cause of delays.

If you have an upcoming interview or a rental contract signing, register at least 1 week in advance to make sure you have your number in time.

Where to Do It

• Register online: the fastest option, no waiting in line, with Vietnamese-language support available. Start at the registration page.
• HD TELECOM's store in Shin-Okubo, Tokyo: suitable if you want staff to check your device and set it up for you in person.
• Ward office / city office: where you handle move-in procedures, health insurance, and My Number — you'll need a phone number to fill out forms there, but they don't issue phone numbers.
• Banks, real estate agencies, workplaces: these are places where you'll actually use your phone number, so make sure you have one before you go.

Common Mistakes

• Buying a data SIM and assuming it comes with a phone number. Data SIMs usually don't include any number, or include a technical number that can't receive SMS. Ask clearly "Can this SIM receive verification SMS?" before buying.
• Using a friend's number to register for a bank account or PayPay. If you two have a falling out or your friend returns to their home country, you lose access to your account and it's very hard to recover.
• Not updating your new number after switching carriers. Banks send OTP codes to the old number, companies can't reach you by phone, and applications get cancelled.
• Letting your contract lapse because your credit card expired. Your number gets cut off, and your LINE and bank links are lost. Check your card's expiration date regularly.
• Residence card photos with glare, blur, or cut-off corners. Take the photo against a dark background, with good lighting, showing all 4 corners and the card number clearly.
• Name on the mailbox doesn't match the recipient's name. The post office won't deliver the SIM. Put your name on the mailbox beforehand.
• Forgetting to cancel your contract before returning to your home country. Charges continue to accrue, creating debt that can affect your ability to return to Japan later.
• Thinking that calling 119 through an internet app works. It doesn't. Only a real mobile phone number can make emergency calls and provide accurate location tracking.

Frequently Asked Questions

Can a data SIM receive a bank's SMS code?

No. A data-only SIM has no phone number, so it can't receive SMS. You need a voice SIM with a 090/080/070 number.

I don't have a Japanese bank account yet — can I still register for a voice SIM?

Yes, if the carrier accepts payment by bank transfer or another method. See payment options on the support page.

I registered LINE with my foreign number — do I need to switch to a Japanese number?

You should. Once your foreign number stops working, you won't be able to receive the verification code to recover your LINE account if you switch or lose your phone.

Can a 050 number be listed on a rental contract?

In theory, yes, but many guarantor companies and real estate agencies require a mobile number (090/080/070) for verification. Having a mobile number will help you avoid complications.

Can I keep my old number when switching carriers?

Yes, through the MNP (number portability) process. You request an MNP code from your current carrier and provide it to the new carrier during registration.

Can I still register for a SIM if my residence card is about to expire?

You can usually still register, but the carrier may limit the contract term based on your card's expiration date and require you to update your card after renewing your residence status.

How many numbers can one person hold?

It depends on the carrier, but the number is limited under Japan's regulations against fraudulent phone use. You shouldn't register a number on someone else's behalf — you bear legal responsibility for that number.

Can I use a phone bought in Vietnam with a Japanese SIM?

Yes, if the device is carrier-unlocked and supports the frequency bands used by Japanese carriers. If it's locked to a foreign carrier, you'll need to unlock it first.

Reference Sources

• Ministry of Internal Affairs and Communications of Japan (総務省) — regulations on identity verification for mobile phone contracts: soumu.go.jp
• National Police Agency of Japan (警察庁) — guidelines for calling emergency number 110: npa.go.jp
• Fire and Disaster Management Agency (総務省消防庁) — guidelines for calling 119: fdma.go.jp
• Japan Post Bank (ゆうちょ銀行) — account opening requirements for foreign residents: jp-bank.japanpost.jp
• Immigration Services Agency of Japan (出入国在留管理庁) — forms and documents related to residence status: isa.go.jp

Important note: regulations from banks, real estate companies, carriers, and administrative agencies may change and vary by region. For procedures related to residence status, insurance, taxes, or bank accounts, please verify directly with the relevant authority (your local ward office/city office, bank branch, or the Immigration Bureau) before submitting your application.

Source Verification Date

The content in this article was cross-checked against the official sources listed above in June 2025. We review this periodically; if you notice any information that has changed, please let our support team know so we can update the article.

Need a Japanese Phone Number Under Your Own Name?

If you've just arrived in Japan and only need internet access for now, a monthly data SIM or eSIM is a quick and simple choice. But if you're about to open a bank account, rent an apartment, or go to a part-time job interview, prepare a voice SIM with a 090/080/070 number early so you don't get stuck partway through.

HD TELECOM (Shin-Okubo, Tokyo) provides Vietnamese-language support throughout the entire registration process, from photographing your documents to setting up the APN. You can view all our plans on the products page, register online here, or read more guides on our blog. If you're not sure which plan to choose, just ask — we'll advise based on your actual needs, without pushing you toward a plan more expensive than you need.