Data-Only eSIM: Do I Keep My Phone Number? (2026)
TL;DR
Yes, you keep your phone number. The PlanJapan eSIM is data only: it provides internet connectivity in Japan only (NTT Docomo network). Your primary SIM card — the one from your home carrier — stays active alongside it. You keep your number, you can receive calls and texts, and you make calls via WhatsApp, FaceTime or LINE using the Japanese data. Nothing changes on the number side.
Why a data-only eSIM doesn't touch your number
This is the number one question travelers ask before buying an eSIM for Japan — and the answer is simple: your phone number has nothing to do with the PlanJapan eSIM.
Here's why. Your phone number is attached to your primary SIM card (the one from your carrier). The PlanJapan eSIM is an additional data plan that sits alongside your existing SIM. It doesn't replace it, doesn't deactivate it, doesn't modify it.
When you install the PlanJapan eSIM on your iPhone or Android:
- Your home SIM continues to manage calls, texts and your number
- The PlanJapan eSIM manages only internet connectivity in Japan (4G/5G NTT Docomo)
- Both lines coexist on your phone — that's the dual SIM principle
You lose nothing. Your number stays the same, your contacts don't move, people can reach you exactly as usual.
How dual SIM works with a Japan eSIM
All iPhones since the iPhone XS (2018) and the vast majority of recent Android smartphones support dual SIM: one physical SIM card + one eSIM. Some models like the iPhone 14 and later (US version) even work with two eSIMs simultaneously, with no physical card at all.
Here's how the two lines split responsibilities in Japan:
| Function | Managed by |
|---|---|
| Internet (4G/5G data in Japan) | PlanJapan eSIM |
| Traditional phone calls | Home SIM |
| Traditional SMS | Home SIM |
| WhatsApp / FaceTime / LINE calls | PlanJapan eSIM (via data) |
| iMessage | PlanJapan eSIM (via data) |
| Phone number | Home SIM (unchanged) |
In summary: data goes through the PlanJapan eSIM, everything else goes through your regular SIM. Your phone automatically knows which line to use for each function, as long as you configure the settings correctly (we explain how just below).
Setup: set PlanJapan eSIM as cellular data
Once your PlanJapan eSIM is installed (takes 2 minutes via QR code — see our complete activation guide), you need to tell your phone which line to use for what.
On iPhone
- Go to Settings > Cellular
- Under "Cellular Data", select your PlanJapan eSIM
- Under "Default Voice Line", leave your home SIM (for outgoing calls)
- Under "iMessage and FaceTime", you can leave your home SIM or both
- Make sure "Allow Cellular Data Switching" is turned off (to avoid using data from your home plan)
On Android (Samsung, Pixel, etc.)
- Go to Settings > Connections > SIM Card Manager
- Under "Mobile data", select the PlanJapan eSIM
- Under "Calls" and "Messages", leave your home SIM
That's it. Your phone now uses Japanese internet via PlanJapan and your home number for calls/texts. Both work simultaneously, without conflict.
Tip: you can configure your eSIM before departure and only activate it upon arrival in Japan. Check our guide on when to activate your Japan eSIM for the best timing.
Making and receiving calls with a data-only eSIM
A data-only eSIM doesn't allow traditional phone calls (GSM calls). But thanks to the internet connection it provides, you have access to all VoIP calling apps — and in practice, that's more than enough.
Outgoing calls (you call someone)
Use WhatsApp, FaceTime, LINE, Telegram or Messenger for your audio and video calls. Quality is excellent on the NTT Docomo network — often better than a traditional phone call. A WhatsApp call uses about 1 MB per minute for audio, 5 MB for video.
Incoming calls (someone calls you)
Two scenarios:
- Via an app (WhatsApp, FaceTime, LINE): you receive the call directly via the PlanJapan eSIM data. No additional cost.
- Via your phone number (traditional call): the call comes in on your home SIM. Your phone rings normally. However, note that receiving a call abroad may incur roaming charges depending on your carrier (typically $1-3/minute). If you have a plan with included roaming, it's free.
Our advice: tell your contacts to reach you via WhatsApp or FaceTime during your trip. It's free on both ends, quality is better, and it works perfectly with the PlanJapan data eSIM.
Receiving verification texts (even without data roaming)
This is a concern for many travelers: "Will I receive my bank verification texts in Japan?"
The answer is yes, in the vast majority of cases. Regular SMS (not iMessages, actual SMS) travel through the phone network, not the internet. Your home SIM continues to receive SMS even if you've disabled data roaming.
Here's what you need to know:
- Incoming SMS: free with all carriers, even abroad. You'll receive your bank verification codes, 2FA codes, reservation confirmation texts.
- Outgoing SMS: may be charged abroad (about $0.25-0.50/SMS). But in practice, you never need to send SMS — use WhatsApp.
- No need to enable data roaming: SMS works independently of internet connectivity. Your home SIM just needs to be in the phone with the line active.
Important: a few rare services send codes via automated voice call instead of SMS. In that case, answering the call on your home SIM may incur roaming charges. If possible, switch to authenticator apps (Google Authenticator, Authy) before departure.
Disable data roaming on your home SIM
This is a crucial step to avoid billing surprises. Even if you're using the PlanJapan eSIM for internet, your phone could switch to your home SIM's data in the background — and roaming charges outside the EU/US are very high.
On iPhone
- Settings > Cellular
- Select your home SIM
- Turn off "Data Roaming"
- Also make sure "Allow Cellular Data Switching" is off
On Android
- Settings > Connections > Mobile Networks
- Select your home SIM
- Turn off "Data Roaming"
With these settings, your home SIM stays active for calls and SMS but uses zero data abroad. All data goes through the PlanJapan eSIM. This is the ideal setup for a trip to Japan with no hidden fees.
Special case: eSIM-only iPhone (dual eSIM)
Since the iPhone 14 (models sold in the United States), Apple removed the physical SIM tray. These iPhones work exclusively with eSIMs — and they can manage two simultaneously.
If you have an eSIM-only iPhone:
- Your primary carrier (e.g., T-Mobile, AT&T or Verizon) is already installed as an eSIM
- You can add the PlanJapan eSIM as a second eSIM line
- The operation is strictly identical to classic dual SIM: one eSIM for calls/texts (your carrier), one eSIM for data in Japan (PlanJapan)
Even newer iPhones (iPhone 15, 16, 17) sold in Europe retain a nano-SIM tray but support up to 8 registered eSIMs (with 2 active simultaneously). Total flexibility.
Note: all iPhones from the XS (2018) to the iPhone 17 are eSIM-compatible. Check in Settings > General > About: if you see an "EID", your iPhone is compatible.
Frequently asked questions
Do I lose my phone number by installing a PlanJapan eSIM?
No, absolutely not. The PlanJapan eSIM is an additional data plan that sits alongside your existing SIM. Your number, contacts, calls and texts remain managed by your primary SIM. Nothing changes.
Can my contacts still call me on my usual number?
Yes. Your home SIM stays active and your number doesn't change. If someone calls your number, your phone rings normally. The call goes through your home SIM (roaming charges may apply for traditional calls — advise your contacts to use WhatsApp or FaceTime).
Do I need to remove my SIM card to install the eSIM?
No. Your physical SIM card stays in your phone. The eSIM is installed digitally via a QR code, with no physical handling. Both lines coexist in your phone thanks to dual SIM.
Can I receive bank verification texts in Japan?
Yes. Regular SMS travel through the phone network (not internet). Your home SIM receives SMS even if data roaming is disabled. Incoming SMS abroad are free with all carriers.
Does WhatsApp keep working with my home number?
Yes. WhatsApp is tied to your phone number, not your internet connection. As soon as you have data (via the PlanJapan eSIM), WhatsApp works normally with your home number. Same for Telegram, Signal and other messaging apps.
What if I have an eSIM-only iPhone (no SIM tray)?
No problem. eSIM-only iPhones (iPhone 14+ sold in the US) manage two eSIMs simultaneously. Your primary carrier occupies one eSIM, and the PlanJapan eSIM occupies the second. Operation is identical to classic dual SIM.
Our recommendation
You keep your number. That's the beauty of a data-only eSIM: it adds an internet connection in Japan without touching your existing phone line. No interruption, no number transfer, no bad surprises.
Before departure:
- Set your PlanJapan eSIM as "cellular data" and leave your home SIM for calls
- Disable data roaming on your home SIM to avoid charges
- Tell your contacts to reach you via WhatsApp or FaceTime — it's free and works perfectly with Japanese data
For a stress-free trip with high-speed internet from landing:
- Standard traveler (Maps, social media, messaging) → eSIM Japan PlanJapan
- Heavy use (streaming, hotspot, remote work) → Unlimited eSIM Japan