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Installing an eSIM is much easier than most people think. With Companion Mobile, the entire process takes under two minutes — and you can do it from the comfort of your home before you even pack your bags. This guide walks you through the installation on both iPhone and Android, step by step.
Before You Start
Make sure you have the following ready before beginning the installation:
- A compatible device: iPhone XS or later (including all iPhone 11, 12, 13, 14, 15, and 16 series), Google Pixel 3 or later, Samsung Galaxy S20 or later, and most flagship Android phones released after 2020.
- A stable Wi-Fi connection: You need internet to download the eSIM profile. Use Wi-Fi — do not try this on cellular data.
- Your QR code or activation code: After purchasing your Companion Mobile plan, you will receive a QR code via email. Have it ready on another device (laptop, tablet, or another phone) or print it out.
- An unlocked phone: Your phone must be carrier-unlocked to use a foreign eSIM. Most phones purchased outright or through Apple/Samsung are unlocked. If you bought your phone through a carrier on a payment plan, contact them to confirm.
Quick compatibility check: On iPhone, go to Settings > General > About. If you see "Available SIM" or "eSIM" listed, your phone supports it. On Android, go to Settings > Network & internet > SIMs > "Add eSIM."
Installing on iPhone
Open Cellular Settings
Go to Settings > Cellular (or "Mobile Data" in some regions). Tap "Add eSIM" or "Add Cellular Plan." Your iPhone will present you with options to set up the eSIM.
Scan the QR Code
Select "Use QR Code" and point your iPhone camera at the QR code from your Companion Mobile email. The camera will automatically detect and read the code. If scanning does not work, you can tap "Enter Details Manually" and type in the activation code provided in your email.
Confirm and Label
Tap "Add Cellular Plan" when prompted. Your iPhone may ask you to label the new plan — choose "Travel" or "Japan" to keep things organized. Set your primary line as the default for calls/messages, and the new eSIM as default for cellular data. This way your home number stays active for calls while the eSIM handles all your data in Japan.
Configure Data Settings
Go to Settings > Cellular > Cellular Data and select your new Companion Mobile eSIM as the data line. Make sure "Data Roaming" is turned ON for the eSIM line (this is required for it to work in Japan). Turn off data roaming on your primary line to avoid unexpected charges from your home carrier.
Installing on Android
The process on Android is very similar, though menu names vary slightly by manufacturer. Here are the steps for most Android phones (Samsung, Google Pixel, OnePlus, etc.):
Open Network Settings
Go to Settings > Network & internet > SIMs (on Pixel) or Settings > Connections > SIM manager (on Samsung). Tap "Add eSIM" or "Add mobile plan."
Scan the QR Code
Select "Scan carrier QR code" and point your camera at the Companion Mobile QR code. The phone will read the code and begin downloading the eSIM profile. This usually takes 30–60 seconds.
Activate and Configure
Once downloaded, tap "Activate" or "Turn on" to enable the eSIM. Go to SIM settings and set the Companion Mobile eSIM as your mobile data line. Keep your primary SIM for calls and texts. Enable data roaming for the eSIM line.
On Samsung Galaxy phones, the path is Settings > Connections > SIM manager > Add eSIM. If you do not see this option, make sure your phone's software is up to date and that it was not purchased as a carrier-locked model.
When to Activate Your eSIM
Timing matters. Here is the recommended approach:
- Install the eSIM before your trip (even a few days before). The eSIM profile is downloaded to your phone but is not yet using data.
- Keep the eSIM line turned off (or disable its data) until you arrive in Japan.
- When you land in Japan, simply enable the eSIM data line and turn on data roaming. Your plan begins when you first connect to a Japanese network.
This approach means you have internet connectivity within seconds of landing — no waiting in airport lines for SIM cards or Wi-Fi rentals. While other passengers are figuring out their connectivity, you will already be checking Google Maps for the best route to your hotel.
Important: Most Companion Mobile plans start counting from first use in Japan, not from the moment of installation. So there is no penalty for installing early — it is actually recommended.
Troubleshooting Common Issues
QR code will not scan
Make sure your camera lens is clean and the QR code is well-lit. If scanning still fails, use the manual activation code provided in your confirmation email. On iPhone, select "Enter Details Manually" during setup. On Android, look for "Enter code manually" or "Activation code."
eSIM installed but no data connection
Check these settings: (1) Make sure the eSIM is set as the mobile data line, not just installed. (2) Verify that data roaming is ON for the eSIM line. (3) Restart your phone. (4) If still no connection, go to Settings > Cellular (iPhone) or Settings > Network (Android) and manually select a network operator (NTT Docomo, SoftBank, or KDDI).
Phone says "No SIM" or "SIM Failure"
This usually means the eSIM profile did not download completely. Delete the eSIM profile and re-scan the QR code on a stable Wi-Fi connection. If the issue persists, contact Companion Mobile support — we respond within minutes.
Can I install the eSIM on two devices?
No. Each eSIM QR code can only be installed on one device. If you need to transfer it to a different phone, contact support for a new QR code. Do not delete the eSIM from your phone unless you are ready to lose it — once deleted, most eSIM profiles cannot be re-installed with the same QR code.
Ready to get your eSIM?
Purchase your Companion Mobile plan and you will receive your QR code instantly by email. Installation takes less than 2 minutes.
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