Vietnam eSIM Guide: WhatsApp & Banking SMS for Travelers

WhatsApp relies entirely on a data connection — it has nothing to do with your phone number's SMS capability. As long as you have an active data plan on your Vietnamese eSIM with 4G or 5G coverage, WhatsApp messages, voice calls, and video calls will work exactly as they do at home. No extra international plan or per‑minute charges apply.

To keep your French WhatsApp number active, simply insert your French physical SIM into the phone alongside the eSIM. WhatsApp will continue to use your French number for registration and display, but all data traffic goes through the eSIM. If you're traveling with friends from other countries, group chats function normally — everyone just needs their own data connection.

French banks like BNP Paribas, Société Générale, and Crédit Agricole typically send validation codes and transaction alerts via SMS to your French mobile number. These messages will still arrive in Vietnam as long as your physical French SIM is inserted in the phone and not in airplane mode. SMS delivery does not require mobile data — the phone uses the SIM's roaming registration on the network, even with data roaming turned off for that line.

To avoid accidental data charges from your French carrier, make sure 'Data Roaming' is enabled only for the Vietnamese eSIM line and disabled for the French SIM. Keep in mind that some French carriers charge for incoming SMS while roaming. For example, Free Mobile charges €0.01 per SMS after exceeding the fair‑use limit. Check your plan's roaming policy before departure.

The most common setup for French travelers is to keep their physical SIM for calls and SMS and use a Vietnamese eSIM for data. Install the eSIM before you leave — after purchase, you'll receive a QR code by email. Scan it with your phone while connected to Wi‑Fi or your home SIM's data.

On iPhone (XS or later): go to Settings > Cellular > Add Cellular Plan. Set the default data line to the Vietnamese eSIM, and the default voice/SMS line to your physical French SIM. On Samsung: open Settings > Connections > SIM card manager. Set mobile data to the eSIM and calls/texts to the physical SIM. If your phone supports dual eSIM (iPhone 13 and newer), you can use a French eSIM plus a Vietnamese eSIM, but physical + eSIM remains the most reliable choice for French travelers.

For a one‑week trip, our Viettel 7‑day plan (5 GB per day at $9.90) gives you plenty of data for WhatsApp, maps, social media, and occasional video calls. The 5 GB daily cap is generous for most travelers. If your trip lasts 10 days, the Vinaphone 10‑day plan (5 GB/day at $11.90) is a solid middle ground; Viettel offers slightly better coverage in remote mountain areas, but Vinaphone works well in cities and along the coast.

For a two‑week stay, the Viettel 15‑day plan (5 GB/day at $12.90) provides the best value per day. All these plans run on 4G/5G networks and include a fair‑use policy (FUP) — typical streaming and video calls remain smooth under normal usage. If you exceed the daily cap, speeds are reduced to 128 kbps (enough for messaging but not video), and the data resets the next day.

If your eSIM doesn't activate after landing: connect to airport Wi‑Fi, go to Cellular settings, and turn on 'Data Roaming' for the eSIM line. It should activate within a minute. If banking SMS aren't arriving despite having your French SIM inserted, confirm that 'International Roaming' is enabled on your French carrier account — you can usually check this by sending a short code or via your carrier's app.

In rural areas, both SIMs may show 'No Service' temporarily. As a backup, keep offline maps downloaded (Google Maps allows offline areas) and consider buying a Viettel eSIM for its broader rural coverage. If you still have trouble, contact our support team at simvietnam.telebox.vn — we're a small local store and happy to help troubleshoot.