Yes, you can keep your Indian SIM active while using a Thailand eSIM on an unlocked, eSIM-compatible dual-SIM phone. This setup allows you to use a separate Thailand connection without changing your existing Indian number or physically swapping SIM cards. You can also manage the two lines independently, making it easier to separate your personal number from your travel connection during the trip.
Before using both lines, check that your phone supports dual-SIM standby and that your carrier allows the Indian line to remain connected while abroad. Also, confirm which line your phone uses for mobile data and calls, as these settings can vary between devices.
What Does Dual-SIM Standby Mean for Your Phone?
Dual-SIM standby (DSDS) allows your phone to keep two SIM lines available at the same time, such as your Indian physical SIM and Thailand eSIM. Both lines can remain registered to their networks while the phone is idle, so you do not need to remove one SIM to use the other.
When you receive a call or message, the phone can identify which number it was sent to. You can also choose the preferred line for different functions through your phone's SIM settings. However, because both lines generally share the phone's cellular resources, some devices may temporarily make the other line unavailable while one SIM is handling a call.
How to Use Your Indian SIM With a Thailand eSIM
Using both lines together lets you separate your regular Indian number from your Thailand connectivity. Keep the Indian SIM available for services tied to your existing number, while the Thailand eSIM provides the connection for your day-to-day internet needs. This setup is especially useful when you want to travel without changing your number or moving your physical SIM to another device.
Will Your Indian SIM Charge Roaming Fees?
Keeping your Indian SIM active does not automatically mean you will be charged roaming fees. However, calls, mobile data, or other roaming services can incur charges depending on your carrier and plan.
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Keep data roaming off on your Indian SIM.
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Check your carrier's Thailand roaming rates before departure.
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Avoid unnecessary calls from your Indian number.
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Use the Thailand eSIM for everyday mobile data.
Can You Receive OTPs on Your Indian Number?
Yes, you can generally receive SMS and OTPs on your Indian number while using the Thailand eSIM for mobile data. This allows you to continue accessing banking, UPI, email, and other services linked to your Indian number without switching your data connection. OTP delivery can depend on your carrier's roaming support, network availability, and SMS service while abroad.
Can You Make and Receive Calls on Your Indian SIM?
You can keep your Indian SIM available for calls while using the Thailand eSIM for internet access. However, calls made or received through the Indian line may be charged at international roaming rates based on your carrier and plan. For everyday communication, you can use WhatsApp or other calling apps over the Thailand eSIM to avoid relying on cellular calls.
How to Set Up Both SIMs on Your Phone
After installing the Thailand eSIM, assign each line a specific purpose. Keep your Indian SIM for your existing number, calls, SMS, and OTPs, while using the Simju eSIM for mobile data. The exact settings may vary depending on your phone model and software version.
iPhone
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Add the eSIM: Go to Settings → Cellular/Mobile Data → Add eSIM and follow the setup instructions.
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Keep your Indian SIM active: Make sure your Indian line remains enabled for calls and SMS.
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Choose mobile data: Select Simju under the mobile-data settings so your Thailand connection handles internet usage.
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Disable Indian data roaming: Turn off data roaming for the Indian SIM to reduce the risk of roaming charges.
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Turn off data switching: Disable Allow Cellular Data Switching so the iPhone does not automatically switch to the Indian line for data.
Android
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Add the eSIM: Open Settings → SIM Manager or your phone's mobile-network settings and add the Thailand eSIM.
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Keep the Indian SIM enabled: Leave your Indian line active if you need calls, SMS, or OTPs.
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Select the data SIM: Set Simju as the preferred SIM for mobile data.
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Disable Indian roaming: Turn off data roaming on the Indian SIM unless you have a suitable roaming plan.
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Disable automatic switching: Turn off automatic mobile-data switching if your device offers this setting.
Managing Your Lines: How to Switch Data or Choose a Number for Calls
Your phone lets you assign different tasks to each SIM, so you can use the Thailand eSIM for data while keeping your Indian SIM available for calls and SMS. These preferences can be changed anytime through your phone's SIM or cellular settings.
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Set Simju eSIM as the default line for mobile data.
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Select your Indian SIM when you want to make calls from your existing number.
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Choose which SIM handles outgoing SMS when prompted.
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Switch the default data line when needed.
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Keep automatic data switching off to prevent accidental use of Indian mobile data.
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Check the selected line before making calls to avoid unexpected roaming charges.
What Happens to Your Indian SIM When You Install an eSIM?
Installing a Thailand eSIM does not affect your existing Indian SIM or phone number. On a compatible dual-SIM device, your physical Indian SIM and Thailand eSIM can remain active together, with each line assigned a different purpose.
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Your Indian number stays active: You can continue receiving SMS and OTPs on your existing number.
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Your physical SIM stays in the phone: There is no need to remove or replace it.
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Calls and SMS: Your Indian SIM can remain enabled for calls and messages.
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Mobile data: Simju can be selected as your primary data line in Thailand.
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Easy control: You can enable, disable, or switch either line through your phone's SIM settings.
What to Check Before Flying to Thailand
Checking your phone and SIM settings before departure helps ensure the Thailand eSIM works smoothly and prevents accidental roaming charges.
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eSIM compatibility: Make sure your phone supports eSIM and dual-SIM use.
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Carrier unlock: Confirm your phone is unlocked and can connect to another network.
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Simju installation: Install the eSIM before departure while connected to Wi-Fi.
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Indian SIM: Keep it active if you need your Indian number for OTPs, SMS, or calls.
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Mobile data: Set Simju as your default data line after arriving in Thailand.
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Roaming: Keep data roaming off on your Indian SIM unless you have a suitable roaming plan.
Simju eSIM vs. a Local SIM: What's Best for an Indian Traveler?
For travelers with an eSIM-compatible, unlocked phone, Simju eSIM offers a simpler setup. You can purchase the plan before leaving India, install it in advance, and activate it after reaching Thailand. Your Indian SIM can remain in the phone, so there is no need to remove or replace it.
A physical Thai SIM is a practical option for phones without eSIM support. You can purchase one after arriving from providers such as AIS, True, or dtac and use it through your phone's physical SIM slot. However, you may need to replace your existing SIM or use a second physical SIM slot.
Overall, Simju is better suited to travelers who want to prepare their connection before departure, while a physical Thai SIM works well for phones that do not support eSIM.
Frequently Asked Questions
Will My WhatsApp Number Change When I Use a Thailand eSIM?
No. Your WhatsApp account remains connected to your Indian number. The Thailand eSIM simply provides the mobile-data connection used by WhatsApp.
Can I Use UPI Apps While Connected to the Thailand eSIM?
Yes. UPI apps can generally use the Thailand eSIM's internet connection. However, some transactions may still require verification through your Indian number or bank.
Can I Receive Bank SMS While Using the Thailand eSIM?
Your Indian SIM can continue receiving SMS while the Thailand eSIM handles data, provided your Indian carrier supports the required roaming connectivity.
Can I Use the Thailand eSIM for Hotspot?
This depends on the specific eSIM plan and provider. Check whether hotspot or tethering is supported before relying on it for another device.
What Happens When the Thailand eSIM Data Runs Out?
Your phone will stop using that eSIM for mobile data once its available data is exhausted. You can then purchase additional data if the plan supports top-ups or switch to another available data option.