A practical setup for mobile data, local calls, and messaging that works in real life, with Viettel as the anchor.
If you want reliable data and a real Vietnam phone number, skip the airport SIM booths, use your international plan for the first day or two, then get a Viettel SIM or eSIM from an official Viettel store with your passport.
Step 1: Do not buy a SIM at the airport
Airport SIM kiosks are notorious for overpriced plans and “tourist” SIMs that are already activated, time limited, or not what you were told you’re buying. Get into the city and do it properly at an official carrier store.
What to do instead
- Land, get through the airport, get to your hotel
- Use your international roaming plan for 1 to 2 days
- Then switch to Viettel
Step 2: Use your international data plan for 1 to 2 days
Airport SIM kiosks are notorious for overpriced plans and “tourist” SIMs that are already activated, time limited, or not what you were told you’re buying. Get into the city and do it properly at an official carrier store.
This buys you time so you can:
- Message your driver or hotel
- Use maps, Grab, and translation apps
- Find a proper Viettel store without stress
Step 3: Install the right messaging apps before you arrive
- Keep WhatsApp for friends and family outside Vietnam.
- Zalo (for Vietnam)
In Vietnam, Zalo is the default. Many local businesses and individuals will expect it. Zalo reports roughly 79 million monthly active users (Sept 2025), and Vietnam media has reported Zalo as the most used messaging app in the country.
If you only use WhatsApp, you will run into moments where the other person simply says: “Do you have Zalo?”
Step 4: Go to Viettel and get a real SIM or eSIM
Bring your passport. Vietnam requires ID registration for SIMs, and Viettel will ask for it.
Ask for
- A prepaid plan with enough data for your stay
- eSIM if your phone supports it and is unlocked
- A quick test before you leave the store (data works, calls work, SMS works)
Step 5: Top up the easy way
In practice, topping up in person is the simplest. Convenience stores and groceries commonly sell top ups or vouchers.
- WinMart top ups are convenient because they are everywhere
- If online card payments fail, do not waste time, just top up in store
Step 6: Keep your Vietnam number for the next trip
Before you leave Vietnam, switch to the cheapest “keep my number alive” approach:
- Move to a low cost prepaid option
- Maintain a small balance and do a tiny usage occasionally
Many travelers keep a Viettel number active by using a basic prepaid package and topping up periodically.
Simple packing list for Vietnam comms
- Unlocked phone (supports eSIM if you want eSIM)
- Passport (for SIM registration)
- WhatsApp installed and verified
- Zalo installed
- A screenshot of your hotel address in Vietnamese (helps when data drops)