FAQ Category JB Data SIM

Is the speed of a physical SIM card faster than an eSIM?

The signal strength is mainly affected by the telecommunications company’s network infrastructure. The factors that influence the signal strength are as follows:

The distance to the base station
Presence of obstacles
Presence of signal interference
Antenna performance
Frequency band Since our company’s eSIM and SIM cards are products from Japan’s local docomo telecom company, using the same signal, the speed of our eSIM and SIM cards are the same. As for other international roaming eSIMs, there may be cases where roaming is done through smaller telecom companies, leading to significant differences in speed and coverage.

Any SIM restrictions？

【 iOS Device】

「settings」➔「General」➔「About」➔「Carrier Lock」 ➔No SIM restrictions

【 Android Device】

You cannot determine this directly from the mobile phone. Please check with the place of purchase or the carrier you have a contract with.
SIM lock regulations vary by country. In Taiwan, most phones are not SIM-locked.Devices purchased in countries like Japan or the United States are more likely to have SIM lock issues.
📢If you have used SIM cards from different countries or carriers, the device is likely not SIM-locked.

Use Your Taiwan Wi-Fi Calling Service in Japan

Taiwan’s major mobile carriers provide Wi-Fi Calling services.

➡ While you are in Japan, Wi-Fi Calling is treated as if you were using your phone in Taiwan.

📲 Receiving calls and SMS: Free

📲 Making calls and sending SMS: Charged at your Taiwan domestic rates

📶 Requirements

・Your phone is connected to Wi-Fi.

・Wi-Fi Calling is enabled on your phone (please refer to the attached guide).

・Your Taiwan SIM card is active.
(No international roaming subscription is required, so you don’t need to worry about additional roaming charges.)

📞 How to Make Calls

Calling a Taiwan number

➡ Dial the Taiwan phone number directly without adding the country code.

Calling a Japan number

➡ Make an international call.
(Example: 009-81-…)

🌟 Benefits

・No need to enable international roaming.

・You can make and receive calls over Wi-Fi even in areas with poor mobile signal, such as indoors.

・The person you’re calling will not know that you’re overseas.

・You can also receive SMS verification codes while abroad.

Can I use multiple SIM cards or eSIMs at the same time?

🅰️ Yes, multiple SIM usage is supported.

If your smartphone supports Dual SIM or multiple SIM functionality, you can use multiple physical SIM cards and/or eSIMs at the same time for more flexible usage.

⚠️ The number of SIM cards/eSIMs that can be used depends on your device model and specifications. Please check your device compatibility before use.

Can I receive Taiwan calls and SMS for free while in Japan?

Yes, you can use this service if the following conditions are met:

✅ Your smartphone is connected to Wi-Fi
✅ The Wi-Fi Calling function is enabled
✅ You are using a supported device (iPhone / Android)
✅ Your SIM card remains active (not suspended or cancelled)

💰 Charges (Important)
Wi-Fi Calling is treated as if you are using the service in Taiwan.

📞 Making calls
・Calling a Taiwan number → Taiwan domestic call charges
・Calling a Taiwan mobile number → Taiwan domestic rates
・Calling overseas (e.g., Japan) → International call charges

👉 No international roaming charges will apply

📲 Receiving calls
・Receiving calls from Taiwan → Free (same as receiving calls in Taiwan)

🌟 Benefits
・Good call quality when the Wi-Fi connection is stable
・You can make and receive calls without enabling international roaming