Your phone is eSIM compatible? Perfect — but there's one more trap to check: the carrier lock, also known as "SIM lock". It's the number one reason an eSIM refuses to install on a phone that's technically compatible. Here's how to check in 30 seconds, and what to do if your phone is locked.
Why a carrier-locked phone refuses an eSIM
A phone bought through a carrier (often with a subsidised plan) can be locked to that carrier's network. In practice, it only accepts SIM cards from the brand that sold it — and rejects all the others, physical SIMs and eSIMs alike. A travel eSIM for Japan looks like a "foreign" SIM: on a locked phone it will be refused at installation or fail to connect to the network. To use a third-party eSIM, your phone therefore has to be unlocked (open to all carriers).
Checking on iPhone: 20 seconds
The "About" menu sits right at the top of the General section.
The line is towards the bottom of the screen, below the device identifiers.
This is Apple's official answer, straight from your phone:
Your iPhone is unlocked: it accepts eSIMs from any carrier, including your Japan eSIM.
Your iPhone is locked to a carrier: request an unlock before buying an eSIM (see below).
Checking on Android: it depends on the brand
On Android there's no universal menu: the information varies by brand and carrier. Two reliable methods:
| Method | How to do it | Verdict |
|---|---|---|
| Test another SIM | Put in a friend's SIM card from a different carrier and restart the phone. | If it picks up the network: phone unlocked. If a code or a lock message appears: phone locked. |
| Ask your carrier | From your online account, the app or customer service, ask whether your phone is locked. | Official, reliable answer — have your IMEI number handy (dial *#06# to display it). |
Getting your phone unlocked: usually free
Good news: unlocking is generally free on request from most carriers — the exact conditions vary from one carrier to another, so check with yours. You do it from your online account or through customer service, using your IMEI number (*#06#). The unlock is done remotely, it's permanent and it deletes none of your data.
Phone unlocked? Check compatibility, then travel with peace of mind
An unlocked phone isn't necessarily eSIM compatible (and vice versa): the two checks are independent. Take 30 seconds to confirm the second one with our checker.
Compatibility checkeriPhone 15, Galaxy S24, Pixel 8… search for your model in our database of 650+ compatible devices, updated every week.
Check my phone →And if your phone still turns out to be locked or incompatible after purchase? You're covered:
Compatibility guarantee: refunded in fullIf your phone isn't compatible after purchase, we refund you 100% — like Romain C., refunded within days (verified review).
Phone unlocked and compatible? All that's left is to choose your Japan eSIM plan — unlimited 10-30 days or 10/20/50 GB, QR code by email in 2 minutes. More questions? Our answers to frequently asked questions cover everything else.
