Data roaming on a Vietnam eSIM: when you need it
- Only if it will not start
- On for the eSIM line
- Off at home
The short answer
These plans run on Vietnamese networks, so data roaming is normally not needed: leave it off. If the eSIM line does not connect, turn data roaming on for the eSIM line and try again; that is the store's own guidance. Keep data roaming off on your home line.
Checked October 2, 2026
When to switch it on
The eSIM connects to the network named on your plan, Viettel, VinaPhone or MobiFone. A line that comes up and moves data needs no switches at all. Should the line fail to connect, switch data roaming on for the eSIM line and try again: the store lists that switch as the remedy when a line will not start.
Where the switches are
On an iPhone: Settings, then Cellular, then the eSIM line, then Data Roaming. Android keeps it in the SIM settings: choose the eSIM, then Roaming. Repeat that on the home line and leave it switched off there.
If it fails (Data roaming)
Signal present but no data? Make sure the eSIM line carries mobile data and has roaming switched on. Then follow not connecting. The plans are prepaid, so this switch cannot add a charge to your plan.
More help
Install your Vietnam eSIM at home, before you fly
Scan the QR code from your order page at home on Wi-Fi, within 30 days of buying, and keep the line off until you land. How to install a Vietnam eSIM.
Switch your Vietnam eSIM on when you land
After landing in Vietnam, switch the eSIM line on and choose it for mobile data. If data does not start, turn on data roaming for that line only.
Vietnam eSIM not connecting: the checks, in order
Is your eSIM not working in Vietnam? Check the line, mobile data and airplane mode, then data roaming, pick the network by hand, and write to support.
Vietnam eSIM refunds: when you get your money back
A full refund when the eSIM fails and no fix exists. A working eSIM is not refunded. How to ask, and where the money goes.
Will this phone run an eSIM? Find out before you buy
Dial *#06#: if your phone shows an EID, it has an eSIM. It must also be unlocked. Check your model before you buy a Vietnam eSIM.
Still stuck?
Orders, QR codes and refunds are handled by VietSIM support. Write with the link to your order page and your phone model.
contact@vietsim.com