When using an eSIM for travel in Japan, many people may feel anxious, asking themselves, "Is it okay to turn on data roaming?" and "Will I incur overseas roaming charges?"
For many travel eSIMs for Japan, it is necessary to turn on data roaming on the Japan eSIM side to connect to the internet. However, if you turn on data roaming for your main line, depending on your contract, you may incur high overseas communication charges.
In this article, we will clearly explain how to set up data roaming on a Japan eSIM for both iPhone and Android. We will also introduce how to differentiate between your main line and the Japan eSIM, as well as how to check if you cannot connect.
Is it necessary to turn on data roaming for Japan eSIM?
Most Japan eSIMs sold for travel are designed to connect to the networks of domestic communication companies in Japan. Therefore, simply adding the eSIM to your device may not allow for communication, and it may be necessary to turn on data roaming on the Japan eSIM side.
Generally, you should set it up as follows:
- Japan eSIM line: Turn on data roaming
- Main line you usually use: Turn off data roaming
- Mobile data communication: Select Japan eSIM
However, the settings may vary depending on the eSIM. Be sure to check the setup instructions that arrive after purchase and the usage information listed on the product page. If you want to check the rates and usage days for Japan, please refer to the Japan eSIM product and pricing plans.
What is data roaming?
Data roaming is a system that allows you to use mobile data communication by utilizing the network of a different communication company than the one you are contracted with.
Data roaming is also used when you take your usual smartphone abroad and connect to a local communication company. On the other hand, in the case of a travel eSIM, data roaming may be used as a mechanism to connect to the local network.
"Turning on data roaming does not necessarily mean that high charges will be incurred." The important thing is which line's data roaming is turned on.
Turn on roaming for the Japan eSIM
If specified for the travel Japan eSIM, turn on data roaming on the Japan eSIM side. Communication charges are generally incurred within the limits of the purchased eSIM plan.
Turn off roaming for the main line
It is generally safer to keep the data roaming for your usual SIM card or main line turned off. If data communication occurs on the main line while abroad, you may be charged additional fees by your contracted communication company.
Basic settings when using Japan eSIM
When using a Japan eSIM, it is necessary to correctly select not only data roaming but also the line used for mobile data communication.
The basic settings are as follows:
- Add the purchased Japan eSIM to your smartphone
- After arriving in Japan, turn on the Japan eSIM line
- Select Japan eSIM for mobile data communication
- Turn on data roaming on the Japan eSIM side
- Turn off data roaming on the main line
- Wait a few minutes and then check the internet connection
If you do not know how to add an eSIM, please also check the eSIM setup guide for iPhone and Android.
How to turn on data roaming on iPhone
On iPhone, you can set data roaming for the Japan eSIM using the following steps. The item names may vary slightly depending on the iOS version.
- Open "Settings"
- Select "Cellular"
- Select the purchased Japan eSIM line
- Turn on "Turn On This Line"
- Turn on "Data Roaming"
Next, go to "Settings" → "Cellular" → "Cellular Data" and select Japan eSIM as the line to use for the internet.
If "Allow Cellular Data Switching" is ON, it may automatically switch to the main line depending on the communication situation. If you want to prevent unnecessary overseas communication, it is safer to keep it OFF.
Settings to check on iPhone
- The Japan eSIM line is ON
- Japan eSIM is selected for mobile data communication
- Data roaming for Japan eSIM is ON
- Data roaming for the main line is OFF
- Automatic switching of mobile data is OFF
How to turn on data roaming on Android
On Android, the names of the settings screens may differ depending on the model and OS. Generally, you can set it up using the following steps.
- Open "Settings"
- Select "Network & Internet" or "Connections"
- Select "SIM," "SIM Manager," or "Mobile Network"
- Select the purchased Japan eSIM
- Turn on the Japan eSIM line
- Turn on "Roaming" or "Data Roaming"
- Select Japan eSIM as the SIM to use for mobile data communication
The settings screens may differ depending on the device manufacturer, such as Samsung Galaxy, Google Pixel, or Xiaomi. If you cannot find the settings, try searching for "roaming" in the search bar of the "Settings" screen.
Please note that not all smartphones support eSIM. Before purchasing, check the list of eSIM-compatible devices for the model you plan to use.
Precautions to prevent overseas roaming charges
Even if you turn on data roaming on the Japan eSIM side, you will usually communicate within the limits of the purchased eSIM plan. However, if the settings for the main line are incorrect, data communication may unintentionally occur using your usual SIM card.
Turn off data roaming for the main line
Before arriving in Japan, make sure to turn off data roaming for your usual main line. If you do not have a plan for overseas use, you may incur pay-per-use charges.
Specify mobile data communication to Japan eSIM
Simply adding the Japan eSIM may leave the mobile data communication line set to the main line. Be sure to check the settings screen to confirm that Japan eSIM is selected as the data communication line.
Turn off automatic line switching
If "Allow Cellular Data Switching" on iPhone or the automatic data switching feature on Android is ON, it may switch to the main line in areas with weak Japan eSIM signals.
To prevent unexpected communication charges, it is recommended to keep the automatic switching feature OFF during your trip.
Be cautious of voice call and SMS charges
Even if you are using the Japan eSIM for data communication, voice calls and SMS may use the main line. Whether charges apply for incoming calls, outgoing calls, and SMS sending depends on the communication company and contract plan of the main line.
If you need calls or SMS, please also check the eSIM with phone number.
If you cannot connect even after turning on data roaming for Japan eSIM
If you cannot connect to the internet even after turning on data roaming, please check the following items in order.
1. Check if the Japan eSIM line is ON
Even if you have added the eSIM to your device, you cannot communicate if the line itself is OFF. Please check the settings screen to confirm that the Japan eSIM line is enabled.
2. Select Japan eSIM for mobile data communication
Check if the data communication line is still set to the main line. On iPhone, check "Cellular Data," and on Android, check "Mobile Data" or "Preferred SIM" settings.
3. Toggle airplane mode ON and OFF
Turning airplane mode ON for a moment and then OFF after about 10 seconds may allow you to reconnect to the communication network.
4. Restart your smartphone
If you cannot connect after setting up the eSIM, please restart your smartphone. Restarting may update the network settings and allow communication.
5. Check APN settings
Some Android devices and eSIM plans may require manual APN settings. Please check that the APN information provided after purchase matches what is entered on your device.
6. Check network selection
Usually, the network selection should be set to "Automatic." If you cannot connect with automatic settings, manually select the communication company listed in the instructions for the purchased eSIM.
7. Check the start date and expiration date
For some eSIMs, the usage period starts from the first connection to the local network. On the other hand, some plans start the expiration date from the purchase date or specified date. Please check if you are within the usage period according to the instructions received at the time of purchase.
For detailed confirmation methods, please refer to troubleshooting for when eSIM cannot connect. If the issue is not resolved, please check eSIM setup and support information before deleting the eSIM.
Data capacity needed when using Japan eSIM
When choosing a Japan eSIM, be sure to check not only the data roaming settings but also the data capacity needed during your trip.
If your usage mainly involves maps, transit guides, translations, and messaging, you can manage with relatively low data capacity. On the other hand, if you frequently watch videos, make video calls, post videos on social media, or use tethering, a large capacity or unlimited plan is recommended.
You can check the estimated data usage for different purposes at estimated data usage. If you are looking for a plan that fits your length of stay and usage, please also refer to comparison of Japan eSIM pricing and plans.
Frequently asked questions about data roaming for Japan eSIM
Will I incur high charges if I turn on data roaming?
If you turn on data roaming on the Japan eSIM side and select Japan eSIM for mobile data communication, you will generally communicate within the limits of the purchased eSIM plan.
However, if data roaming for the main line is ON or if the data communication line switches automatically, you may incur charges for the main line.
Is it okay to turn on data roaming before arriving in Japan?
Even if you turn on the data roaming setting for the Japan eSIM side in advance, communication usually does not start until you connect to a compatible network in Japan.
However, the conditions for starting usage may vary by eSIM plan. If the instructions received after purchase state "Start using from installation," please follow those instructions.
Should I turn off the main line?
Completely turning off the main line may prevent you from receiving calls or SMS verification on your usual phone number. If you want to maintain your phone number, you can keep the main line ON while turning off data roaming for the main line.
However, since there may be charges for receiving calls and SMS, please confirm with your contracted communication company in advance.
The data roaming option is not displayed
On some devices, the data roaming option may not be displayed unless the eSIM line is ON. Please enable the Japan eSIM line first and then check the mobile network settings.
Is it okay to delete and reconfigure the Japan eSIM?
Even if you cannot connect, do not delete the eSIM before contacting support. The eSIM QR code may only be scanned once. Deleting it may prevent you from reinstalling it, so please be cautious.
For other questions, please refer to frequently asked questions about eSIM. If you want to review everything from how to choose a Japan eSIM to setup methods, please also refer to the complete guide to Japan eSIM.
Conclusion | Let's turn on data roaming for Japan eSIM
For travel Japan eSIMs, it may be necessary to turn on data roaming to connect to the domestic communication network in Japan.
When setting it up, be sure to check the following points:
- Turn on data roaming on the Japan eSIM side
- Select Japan eSIM for mobile data communication
- Turn off data roaming for your usual main line
- Turn off automatic switching for data communication
- If you cannot connect, do not delete the eSIM immediately
The setup methods may vary depending on the eSIM you use and your smartphone. Please check the setup instructions that arrive after purchase and enable the correct line after arriving in Japan.
If you are preparing for a Japan eSIM, you can check plans that fit your length of stay and usage at Japan eSIM product and pricing plans.
