Samsung Galaxy S25 Ultra eSIM in Vietnam – Does it work?

The Samsung Galaxy S25 Ultra supports eSIM through the standard Android interface: go to Settings > Connections > SIM manager to add a mobile plan. This is based on publicly available Samsung specifications — we have not performed our own hardware tests, but the feature is widely documented for all non-China models.

Our Viettel and Vinaphone eSIMs work with the S25 Ultra from any region except mainland China (model SM-S9380 lacks eSIM hardware). US, Korean, and European variants are plug-and-play. Japanese carrier-locked models from docomo, au, or SoftBank typically allow a secondary eSIM for data, but you should confirm with your carrier that the phone is unlocked for eSIM use. No custom APN settings are required — just scan the QR code and activate.

After purchasing a Viettel or Vinaphone eSIM from our store, you will receive a QR code via email. On your S25 Ultra, open Settings > Connections > SIM manager > Add mobile plan. Scan the QR code in good lighting. Alternatively, you can enter the activation code manually. The plan activates immediately; you do not need to reboot.

We recommend installing the eSIM before you depart, or upon arrival using hotel or airport Wi-Fi. The QR code remains valid for 24 hours from purchase. If it expires, contact our support team within 7 days for a replacement — your plan remains active. After installation, test by opening Google Maps or any website; mobile data should work immediately.

The S25 Ultra supports dual SIM operation: one physical SIM plus one eSIM, or two eSIMs simultaneously. This lets you keep your home number active for OTPs and banking SMS while using the Vietnam eSIM for data and local calls (incoming only). For example, you can retain your home carrier on the physical SIM and set the Vietnam eSIM as the default for mobile data.

International travelers benefit greatly: Korean users can keep KT/SKT numbers for SMS verification; Japanese users retain docomo/au/SoftBank for SMS while using Vietnam data; and any traveler can receive OTPs from their home bank. Note that the Vietnam eSIM number (Vinaphone plans) can receive incoming calls and SMS but cannot make outgoing calls — so use WhatsApp, Zalo, or other VoIP apps to call back. Enable 'Allow switching mobile data' in SIM manager to automatically fall back to your home SIM if the Vietnam eSIM loses signal.

For short trips of 1–2 weeks with heavy data usage, the Viettel 15-day plan at $12.9 (5GB/day) is a solid option. If you need a local Vietnamese phone number to receive calls from Grab drivers or hotels, choose the Vinaphone 15-day plan at $13.9 (5GB/day) — it includes a number that can receive incoming calls and SMS. For longer stays, the Viettel 30-day plan at $18.9 (5GB/day) suits digital nomads, while the Vinaphone 10-day plan at $11.9 (5GB/day) is a cheaper choice for shorter visits if you want a number.

Both carriers offer 5GB of high-speed data per day, then reduce speed but remain usable for messaging and maps. Viettel generally has strong urban coverage with fast data speeds, while Vinaphone covers a large portion of rural areas — choose Viettel for city use and Vinaphone if you plan to travel off the beaten path. The price difference is minimal, so your decision should hinge on whether you need a phone number (Vinaphone) or prioritize speed (Viettel). All eSIMs are data-only and cannot be topped up; to extend service, purchase a new plan.

If the eSIM does not activate after scanning, double-check that you are in the correct menu: Settings > Connections > SIM manager > Add mobile plan. Ensure the QR code is scanned in good light and that your phone's region supports eSIM (mainland China models do not). If you see no signal in Vietnam, enable data roaming for the eSIM line in the SIM manager. Some Japanese carrier-locked devices require an unlock before eSIM will work.

For dual-SIM setups, set the Vietnam eSIM as 'Preferred SIM for mobile data' to avoid accidentally using your home SIM's roaming. For calls, you can set 'Ask every time' or default to a specific SIM. If the QR code expired within 7 days, contact our support team for a new code — your original plan remains valid. If the problem persists, verify that your S25 Ultra model is not the China version (SM-S9380), which lacks eSIM hardware entirely.