Data roaming in Vietnam: what Australians should know before they fly
· Telroo
Short answer: your Australian phone can roam in Vietnam with Telstra, Optus or Vodafone, usually for a daily fee that includes data, calls and texts on your own number. A prepaid travel eSIM is the other common choice: a separate data-only line, paid for once, for an eSIM-capable and carrier-unlocked phone. Vietnam plans have one detail that is easy to miss: their data reaches the internet through Hong Kong, so some websites may think you are there.
This article explains how each option works. For plan sizes and current prices, use the Vietnam eSIM guide.
Roaming in Vietnam with an Australian carrier
Vietnam is an eligible roaming destination with all three main carriers. Their own roaming pages, checked on 24 October 2026, describe these options:
| Carrier | Option and zone | What the page says |
|---|---|---|
| Telstra | International Roaming Day Pass, Zone 2 (includes Vietnam) | $10 per day with 2GB of data a day and unlimited standard calls and SMS |
| Optus | Optus Daily Roaming, Zone 1 (includes Vietnam) | $5 for 5GB to use within 24 hours, with unlimited standard talk and text, on Choice Plus, Plus Family and Plus Promo plans |
| Vodafone | $5 Roaming (Vietnam listed as a $5 Roaming destination) | $5 extra per day to use your plan's included data, calls and texts, on eligible plans, for up to 90 days a calendar year |
These are post-paid options; prepaid services have their own packs and rates. Check the page for your exact plan before you go.
When a roaming day is charged
Telstra's page says Day Pass charges apply on days your service is used overseas to make or receive calls, send an SMS or use data, including background data, and that receiving an SMS does not trigger the charge. Optus says Daily Roaming is activated automatically in eligible destinations. Vodafone says $5 Roaming activates automatically when you turn on your phone in an eligible destination.
So the setting that matters is data roaming on your Australian line. Leave it on and background app updates can make a day chargeable. Turn it off if you are using a travel eSIM for data.
Roaming suits you if you need normal calls on your Australian number all trip, your phone cannot take an eSIM, or your plan already includes Vietnam. Travel eSIM or international roaming compares the two in more detail.
How a Vietnam travel eSIM works
A travel eSIM adds a second line that carries data only. You install it in Australia on Wi-Fi, then switch mobile data to it in Vietnam. Your Australian SIM stays in the phone.
What the Telroo Vietnam plans listed on their product pages on 24 October 2026:
- Networks: Viettel Mobile 5G and Vinaphone 5G, on both the fixed-data and the daily plan.
- Data only: no Vietnamese number, standard calls or SMS. Apps such as WhatsApp and Zalo work over data.
- Hotspot: allowed, using the same allowance.
- Top-ups: Top up eligible plans from your order page, subject to eligibility. For eligible Daily plans, top-ups extend the number of days; they do not increase the daily high-speed allowance or remove today’s speed reduction. Keep your existing eSIM installed.
- Use-by: use the eSIM within 180 days of purchase. When validity starts depends on the plan, so read its activation instructions before installing.
Coverage depends on the network, your phone and where you are. The Vietnam guide notes that major cities and common tourist routes can perform differently from rural, mountainous or island areas. Telroo sells these plans; this is a description of what they include, not a coverage or speed test.
Why a website may think you are in Hong Kong
The fixed-data Vietnam eSIM lists Hong Kong as its data exit country, and the Vietnam guide recorded the same for both Vietnam plans on 17 October 2026. Your phone connects to a Vietnamese network, but your traffic reaches the internet through Hong Kong.
What that can change:
- search results, ads or a site's language may be set for Hong Kong;
- some streaming or shopping services may show a different catalogue or store;
- a bank or app may ask you to confirm a sign-in from an unexpected country.
What it does not change: which Vietnamese network you use, and maps or ride-share apps that use your phone's own location. Keeping your Australian line on for SMS codes helps with sign-in checks. What a data exit country means covers this in full.
Fixed data or daily "unlimited"
The two Vietnam plans work differently:
- Fixed data gives one total allowance for the validity period. Use more on a day of long transfers and less on a beach day; it does not reset.
- Daily (Unlimited) gives a high-speed allowance every 24 hours. After it is used, data continues at a reduced speed until the reset: 1 Mbps on the 1GB and 3GB a day options, 384 Kbps on the 5GB and 10GB a day options. You are not cut off, but it is not unlimited full-speed data. Choose enough days when you buy.
Which suits you depends on how evenly you use data. The Vietnam guide's plan table shows both side by side with a per-day figure for trips of up to two weeks, and how much travel data do I need helps you estimate from your own use.
Setting it up before you fly
- Check your phone supports eSIM and is carrier-unlocked (compatibility guide).
- Install the eSIM on reliable Wi-Fi before you leave, if the plan's instructions allow it.
- When you land, set the travel eSIM as your mobile data line and turn on data roaming for that line if its instructions say so.
- Turn off data roaming on your Australian line, and keep that line switched on if you want texts.
The detailed steps are in the iPhone guide and the Samsung guide. For keeping your number, see keeping your Australian number while using a travel eSIM.
Vietnam plus Cambodia or Thailand on one trip
Many itineraries cross a border. Check every country before you buy.
- Roaming: Telstra's Zone 2 and Optus's Zone 1 lists both include Cambodia and Thailand as well as Vietnam. Vodafone's destination list showed Thailand under $5 Roaming but Cambodia under Pay As You Go roaming, so the daily option would not apply there.
- Travel eSIM: the Telroo Vietnam plans cover Vietnam only. The Southeast Asia regional plan covered Indonesia, Malaysia, Singapore, Thailand and Vietnam on 24 October 2026, but not Cambodia. For Cambodia, the Cambodia eSIM guide lists separate plans. If your phone can store more than one eSIM, you can install both and switch mobile data at the border.
Before you go: weather and Wi-Fi
Smartraveller's Vietnam page (updated 24 September 2026, checked 24 October 2026) says storm season is usually from June to November, and that heavy rain, floods, landslides and typhoons can affect flights, roads, power, transport and phone services. In that period, save tickets, bookings and offline maps on your phone before long trips.
It also warns that devices and data can be stolen when using public Wi-Fi, computers or Bluetooth.
Common questions
Does a Vietnam travel eSIM give me a Vietnamese number? No. Telroo plans are data-only. Your Australian number stays on your Australian SIM.
Why do Google results look like Hong Kong? Because the plan's traffic exits through Hong Kong. Allowing your browser to use precise location, or choosing your country or region in the site, can help.
Is the daily plan full speed all day? Only until the daily high-speed allowance is used; then speed is reduced until it resets.
Can I top up my eSIM? Top up eligible plans from your order page, subject to eligibility. For eligible Daily plans, top-ups extend the number of days; they do not increase the daily high-speed allowance or remove today’s speed reduction. Keep your existing eSIM installed.
What if the eSIM does not connect? Do not delete it. Check it is selected for mobile data and that roaming is on for that line, then use the troubleshooting checklist or contact us. The Refund Policy explains how problems are handled.
See plans
Sources and last checked
Checked 24 October 2026. Carrier terms and prices change; check the carrier's page before you travel.
- Telstra, International Roaming: Day Pass zones and prices, when a day is charged.
- Optus, International Roaming: Optus Daily Roaming, Zone 1 destinations, eligible plans.
- Vodafone, International Roaming: $5 Roaming terms and destination list.
- Smartraveller, Vietnam travel advice (updated 24 September 2026): storm season and phone services, public Wi-Fi.
- Telroo product pages and guides linked above: networks, data exit country, daily speed limits, hotspot and regional coverage.