Understanding Data-Only eSIMs
, by Sim Du Lịch AVIRO, 6 min reading time
Data-only eSIMs are a popular choice for travelers due to their flexible internet access without the need for a physical SIM card. But can this type of eSIM make calls? This article will provide you with the answer, as well as instructions on how to use an eSIM for communication while traveling.
What is a data-only eSIM? Can it make calls?
Source: Pexels
Simply put, a data-only eSIM is a type of SIM card that provides only mobile data for internet access, without an associated phone number and without supporting traditional calls or SMS.
The main difference between a data-only eSIM and a regular eSIM lies in their communication functions. While a regular eSIM (usually issued by a domestic carrier) has its own phone number and fully supports calls, texts, and internet access, a data-only eSIM is optimized for internet access needs, typically used for international travel or short-term requirements.
However, you can still communicate normally through applications, as long as you have an internet connection. These are Voice over Internet Protocol (VoIP) applications such as WhatsApp, Viber, Zalo, Skype, etc., which support both audio and video calls. In fact, many people only need to use a data-only eSIM to stay in touch during their trips without needing a physical SIM or their primary phone number.
How to make calls with a data-only eSIM while traveling
Below, Aviro will guide you through some common ways to make calls when using a data-only eSIM.
1. Call via OTT messaging apps
Source: Pexels
Popular messaging apps like WhatsApp, Zalo, Facebook Messenger, Telegram, Viber, and LINE all support voice and video calls over the internet. As long as you and the recipient both have the app installed, connecting will be easy and completely free, regardless of which country you are in.
Advantages:
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Familiar interface, easy to use
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No local phone number needed
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Supports video calls and sending files, photos
Note: Some applications (like WhatsApp) require an initial phone number verification, so you should activate and log in before switching to a data-only eSIM.
2. Use VoIP apps to call phone numbers
If you need to call landline or mobile numbers, you can use VoIP (Voice over IP) services such as:
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Skype: Allows calling any phone number worldwide at a low cost. You can purchase minute bundles or add credit to your account.
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Google Voice (only supported in some countries): Allows you to make and receive calls through your own Google number.
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TextNow, Talkatone: Provides you with a virtual phone number to make calls, primarily supported in the US and Canada.
Advantages:
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Can call any phone number, even those not using the app.
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Much cheaper than international roaming calls.
Note: Some services require account setup in a specific country (e.g., Google Voice in the US). You should carefully check the terms of use beforehand.
3. Tips for making effective calls with a data-only eSIM
In addition to knowing the apps, you can apply these tips to make calls and texts with an eSIM smoother:
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Prioritize stable Wi-Fi
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Use 4G/5G networks instead of 3G for better audio quality
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Turn off bandwidth-hungry apps like YouTube, Netflix, Facebook, TikTok, Spotify, or background data downloading apps
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Consider regularly updating phone software and calling apps to avoid errors
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Use a quality headset with a microphone for clear sound and noise reduction
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Ensure your phone battery has sufficient charge to maintain stable performance
Instructions for activating and using a data-only eSIM
Source: Canva
Before purchasing an eSIM, you need to check if your device supports eSIM.
You can buy a travel eSIM from service providers like Aviro. After payment, a QR code or activation code will be sent via email within minutes.
Next, My SIM will guide you on how to use your primary phone number with a data-only eSIM while traveling:
1. Keep the primary SIM always on (do not remove or turn off)
Even if you are using an eSIM for internet access, make sure your physical SIM (or primary eSIM) – which contains your phone number – remains on. If you remove the SIM or turn it off in the settings, you will not be able to receive/make calls and receive SMS with this number.
2. Turn off “Data Roaming” for the primary SIM
Go to Settings > Cellular (or Mobile Network) on your phone and turn off "Data Roaming" for the primary SIM. This prevents your SIM from automatically using international data and incurring high charges.
Additionally, to ensure you are not using a roaming package, actively call customer service or check your account to make sure you haven't automatically activated this package.
3. Turn on the data-only eSIM and select it as the primary mobile data source
To use the internet abroad and avoid roaming charges, as soon as you arrive, turn on your travel eSIM and ensure that in Settings > Mobile Data, you have selected the eSIM as the default mobile data source. Specifically:
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For iPhone: enable Data Roaming for the eSIM.
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For Android: select the eSIM as the primary SIM for mobile data.
4. Configure the primary SIM for calls and messages
To ensure you still receive/send messages or calls with your original phone number, do the following:
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On iPhone: Go to Settings > Cellular > Default Line > iMessage & FaceTime, select the primary SIM.
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On Android: Go to Settings > Mobile network > Calls & Texts, select the primary SIM.
Note: You must enable data roaming on your primary SIM in Vietnam before going abroad.
5. International call and SMS considerations
Even when you use an eSIM for data, calls or texts made with your primary SIM abroad will still incur international charges at your carrier's rates. It's best to prioritize calling via apps (like WhatsApp, Zalo, Viber, Messenger...) to save costs!
Data-only eSIMs are a smart choice to stay connected when traveling internationally, avoid roaming fees, and still make calls over the internet using popular apps. With proper setup, you'll have a seamless experience throughout your trip. If you still don't have a data-only eSIM, contact My SIM immediately via email avirosim@gmaill.com or Zalo 0384.909.454 on our website!
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