Switch your Vietnam eSIM on when you land
- Line on
- Mobile data on the eSIM
- Roaming only if needed
The short answer
Once you land, bring the eSIM line up and give it the mobile data role. When data refuses to start, switch data roaming on for that line and retry. On the home line, data roaming stays off so nothing can run up charges.
Checked October 2, 2026
On the eSIM line
Switch the line on and make it the one that carries mobile data (on an iPhone this is Cellular Data). When data refuses to start, switch data roaming on for the eSIM line and retry. Stop the phone from moving data between lines: switch that option off, so the home line is never the fallback.
On your home line
Over on your usual SIM, data roaming goes off. Calls and texts to your own number can keep arriving, since the line stays on; your home carrier bills them.
Give it a minute
Allow the phone a minute or two to lock onto the network. The signal bars and the network’s name appear next to the eSIM line: it is the network your plan names, Viettel, VinaPhone or MobiFone.
If it fails (Switch it on after landing)
Run through not connecting in the order given. The install window closes 30 days after buying; when the trip begins after it, contact the store’s support first.
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.
Data roaming on a Vietnam eSIM: when you need it
The plans run on Vietnamese networks, and the store says switch data roaming on for the eSIM line only when it does not connect. Where the switch is.
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