Keep your home number active with Vietnam eSIM

Nearly all modern smartphones support dual SIM operation: either one physical SIM plus one eSIM, or in the case of iPhone 13 and newer, two active eSIMs. When you install our Vietnam eSIM, it becomes your second line. Since the eSIM we sell is data-only, it handles mobile internet while your home SIM (physical or eSIM) continues to handle voice calls and SMS.

Dual SIM Dual Standby (DSDS) means both lines are active and reachable at the same time, but only one can use mobile data at any given moment. To avoid surprise roaming charges, assign the Vietnam eSIM as your default data line and keep data roaming turned OFF on your home SIM. Your home line will still receive calls and texts over its own cellular connection, even while the Vietnam eSIM is handling your internet traffic.

Yes. Incoming SMS to your home number are typically free to receive when roaming (check with your home carrier for any exceptions). That means banking one-time codes, verification messages from apps, and casual texts will arrive exactly as they do at home. Most carriers do not charge for receiving SMS while overseas, but some—especially in parts of Asia and Eastern Europe—may apply a small fee.

Incoming calls ring as usual too. Outbound calls made from your home number will be billed at your carrier’s roaming rate, which can be expensive. To reduce costs, enable WiFi Calling on your home line before you travel. Once you're in Vietnam, WiFi Calling can route calls and texts over the data connection provided by the Vietnam eSIM, often at your domestic rates. Banking SMS and 2FA codes work without issue as long as your home number remains active on the network.

Not all phones can run a Vietnam eSIM alongside a home SIM. iPhone models from XS, XS Max, and XR onward (sold in the US, Europe, Korea, Japan) support eSIM. However, mainland Chinese, Hong Kong, and Macau iPhone variants do not have eSIM hardware. On the Android side, Samsung Galaxy S20, S21, S22, S23, and S24 series (except some carrier-locked handsets) support eSIM, as do Google Pixel 3 and newer (though Pixel 3 support varies by region).

Dual SIM capability also depends on your phone: iPhone 13 and later can hold two active eSIMs simultaneously; older models use one physical SIM plus one eSIM. If you are unsure whether your phone supports eSIM, check your device’s IMEI with a free eSIM checker online. This will confirm if your specific model and region allow eSIM activation.

Buy your Vietnam eSIM before you depart. You will receive a QR code by email. Before traveling, go to Settings > Cellular > Add Cellular Plan on iPhone (or the equivalent on Android) and scan the QR code. You can install it in advance—the eSIM only activates when it detects the Vietnamese network after you land.

After installation, set the Vietnam eSIM as your primary data line. Keep your home line selected for voice and SMS (default voice line). On iPhone with dual eSIM, go to Cellular > Default Voice Line and choose your home number. Turn off data roaming on the home SIM to prevent accidental charges. Before leaving home, test that both lines show signal and that data works on the Vietnam eSIM—the eSIM will usually connect to a non-Vietnamese network in roaming mode during testing, which is normal but may incur a small data charge depending on your home carrier’s policy.

Korea (KT/SKT/LG U+): You must enable international roaming on your home SIM for SMS to work. Services like KakaoTalk phone verification rely on your Korean number being reachable. Japan (docomo/au/SoftBank): Turn on international roaming before departure. Some carriers require you to purchase a roaming package to avoid high per-use charges, even for incoming SMS.

China mainland: iPhones sold in China do not support eSIM, so you cannot use our Vietnam eSIM with a Chinese iPhone. A physical SIM is the alternative. For USA/Canada carriers: most allow free incoming SMS while roaming, and no special settings are needed. France (Orange, SFR, Bouygues, Free): incoming SMS are free; incoming calls generally are not included in standard plans, so advise friends and family to use messaging apps. Russia (MTS/Beeline/Megafon): incoming SMS may incur a charge. Consider purchasing a roaming add-on or enable WiFi Calling before departure to keep costs low.