In recent years, more and more travelers have switched to using eSIMs when going abroad. The convenience is hard to beat—you don’t need to swap physical SIM cards, purchasing and activation are fast, and the cost is often more affordable than traditional roaming. You can even buy an eSIM just minutes before boarding your flight. However, one common concern remains: “If I use an eSIM for data overseas, can I still receive SMS codes—like bank OTPs—sent to my home number?” This article explains how eSIMs work in combination with your original mobile number, what settings are required, and why—especially in countries that have shut down 3G networks—you should always confirm details with your home carrier before traveling.
- 1. What Is an eSIM, and Why Is It Becoming So Popular?
- 2. Why Can’t I Receive SMS or Calls While Abroad?
- 3. How to Set Up eSIM for Data and Keep Your Number
- 4. Wi-Fi Calling and VoLTE: What Are They?
- 5. Does enabling VoLTE or Wi-Fi Calling cost additional fee?
- Conclusion
1. What Is an eSIM, and Why Is It Becoming So Popular?
An eSIM is a digital SIM embedded in your smartphone. It works exactly like a physical SIM card but doesn’t require any swapping or insertion. By scanning a QRCode from your carrier or an eSIM provider, you can add a new mobile plan directly to your device.
For travelers, the biggest advantage is that you can keep your original SIM/eSIM in your phone while adding an overseas data plan via eSIM. This allows you to enjoy data without roaming fee while still allowing your home number to receive calls and SMS authentication codes.
The most common setup abroad is simple: your original number handles SMS and calls, while the eSIM handles your mobile data. This arrangement is not only convenient but also helps ensure you won’t miss important messages or calls.
2. Why Can’t I Receive SMS or Calls While Abroad?
If you're trying to receive calls or SMS messages on your original mobile number while using a travel eSIM, the travel eSIM is usually not the cause. In most cases, the issue is related to your home SIM, your mobile carrier's roaming support, or your device settings.
Below are the most common reasons why this happens.
3G Network Shutdowns and VoLTE Roaming
Many countries—including Australia, Japan, the United States, and Singapore—have retired their 3G networks. As a result, older roaming methods that relied on 3G are no longer available.
If your carrier doesn't support international VoLTE roaming—or if VoLTE isn't enabled or provisioned for your device, SIM, or mobile plan—you may not be able to make or receive calls. SMS delivery may also be affected, depending on how your carrier handles roaming.
Other possible causes include international roaming not being enabled on your mobile plan, account or billing issues (such as a missed payment or suspended service), or your home SIM being turned off in your phone's cellular settings.
3. How to Set Up eSIM for Data and Keep Your Number
To allow your eSIM to handle cellular data while your home SIM remains responsible for calls and SMS, follow these steps:
- Set your eSIM as the Cellular Data line.
- Set your home SIM as the default line for calls and SMS.
- Confirm with your home carrier that your plan supports international roaming and VoLTE roaming, and that these services are enabled if required.
If you are traveling to a destination that has phased out 3G networks (such as Japan), follow the steps below to configure your device:
＊Wi-Fi Calling may use more battery depending on network conditions. If you don't need it, you can turn it off to help conserve battery.
- Go to Settings > Cellular
- Select your primary (home) SIM
- Tap Wi-Fi Calling
- Turn on Wi-Fi Calling on This iPhone
Once configured, swipe down to open Control Center. In the top-left corner, you should see one of the following:
- [Carrier Name] using Cellular Data: Your home SIM's calls and SMS are being carried over your eSIM's mobile data connection using Wi-Fi Calling.
- [Carrier Name] Wi-Fi: Your home SIM's calls and SMS are being carried over a local Wi-Fi network using Wi-Fi Calling.
Android setup
- Go to Settings > Network & Internet or Connections
- Tap SIMs or SIM Manager
- Select your primary (home) SIM
- Enable Wi-Fi Calling
- Set your eSIM as the default for mobile data
Because roaming support, carrier policies, and network compatibility vary by provider and region, we recommend contacting your home carrier before you travel. Please confirm whether your plan supports VoLTE and Wi-Fi Calling, and check any applicable roaming rates to ensure uninterrupted access to calls and SMS abroad.
If you rely on SMS verification codes for banking or other security services, we also recommend setting up alternative verification methods (such as email or authenticator apps) with your providers in advance.
4. Wi-Fi Calling and VoLTE: What Are They?
Wi-Fi Calling lets you make and receive calls and SMS over a Wi-Fi network instead of a mobile signal. It is especially useful in areas with weak cellular coverage and when traveling abroad. In many cases, it can help reduce or avoid roaming charges for calls and SMS, depending on your carrier’s policies and plan.
VoLTE (Voice over LTE) is a technology that enables voice calls to be made over 4G/LTE networks instead of older 2G or 3G networks. It provides clearer call quality, faster call setup times, and allows voice and data to work simultaneously on supported devices. In many countries where 3G networks have been phased out, VoLTE is required for making and receiving calls. However, VoLTE must be supported by both your mobile carrier and your device, and it may need to be enabled in your phone settings or activated on your plan.
5. Does enabling VoLTE or Wi-Fi Calling cost additional fee?
There is typically no extra fee to enable VoLTE or Wi-Fi Calling, depending on your carrier policies. However, your actual usage (calls, SMS, or roaming) may still be charged according to your carrier’s plan, call destination, and roaming conditions. Any applicable roaming charges will depend on your provider’s pricing and how you use your service while abroad.
Conclusion
Using an eSIM for mobile data while traveling does not, by itself, prevent you from receiving SMS or calls on your original number. As long as your home SIM remains active and is able to register on a foreign network, incoming calls and SMS messages will generally continue to work.
However, in countries where 3G networks have been phased out, these services may depend on VoLTE roaming or Wi-Fi Calling, depending on your carrier and device compatibility. Because support varies by provider, region, and device, it is recommended to confirm your carrier’s roaming, VoLTE, and Wi-Fi Calling support before traveling.
Once properly configured, your eSIM can handle mobile data while your home SIM remains available for calls and SMS.
⚠️ This article is based on real-world testing and general usage and is provided for reference only. Actual roaming services and charges depend on your destination, carrier, and plan. Additional charges may apply for calls, SMS, or data usage. Please confirm details with your carrier before traveling.
