Disclaimer: The prices and information presented on this page reflect a snapshot at the time of research and may change at any time without prior notice.
Aisha
06 March 2026
You land at Noi Bai International Airport in Hanoi after a three-hour flight from Singapore, grab your bags, and open Google Maps to find the taxi rank. That is the exact moment most Singtel customers discover their data roaming is not activated, or that they are connected to the wrong local network and burning through credit at pay-as-you-go rates. Vietnam has four main mobile operators and Singtel's ReadyRoam plan only works on two of them. Getting that detail wrong is an expensive mistake. This guide covers exactly how Singtel roaming works in Vietnam, what your ReadyRoam options are, what the AEST reset quirk means for Singaporeans, and when it makes more sense to switch to a dedicated travel eSIM for the duration of your trip.
Vietnam has four active mobile networks: Viettel, Vinaphone (VNPT-I), MobiFone, and Vietnamobile. Singtel has roaming agreements with two of them: MobiFone and Vinaphone. When you land, your phone should automatically connect to one of these preferred networks. If it connects to Viettel or Vietnamobile instead, your ReadyRoam plan data will not work and you will be charged at pay-as-you-go rates. Singtel's Network Lock feature, which is included by default on all ReadyRoam plans, is designed to prevent exactly this situation by blocking data on non-preferred networks. That said, in rural areas, on islands like Phu Quoc, or in mountainous regions near Sapa, Viettel's signal is often the strongest, which means your Network Lock may restrict your data just when you need it most.
For postpaid Singtel customers, Vietnam falls under the Asia roaming zone. The main options are the ReadyRoam plans, which bundle a set amount of data valid for up to 30 days across 18 or more destinations, and the daily UnlimitedRoam and DataRoam plans, which are activated per day and include a 15 GB fair-use threshold before speeds are reduced. All plans are purchased through the My Singtel app. Prepaid users on the hi! plan can buy short-term Asia DataRoam packs through the hi!App. Neither data roaming plan covers calls or SMS by default. For voice coverage, the separate SMSVoiceRoam Asia plan applies.
One practical detail to know: if you are on a non-Upfront Singtel plan, your day pass validity resets at 11:59 PM Australian Eastern Standard Time (AEST), not at midnight Singapore time. Given that Singapore is three hours ahead of AEST, your roaming day effectively ends at 2:59 AM SGT. For an evening out in Ho Chi Minh City that runs past midnight, this can mean your data cuts off mid-Google Maps before you find your way back to the hotel.
Research: March 2026. Prices and plans subject to change. Always verify current rates in the My Singtel app before your trip.
Buy before you board. All ReadyRoam plans must be purchased within 30 days of your intended start date and can be activated in advance. Set your start date to the day you land so you are not wasting validity days during transit.
Check your preferred network manually. Once you land, go to Settings > Mobile Data > Network Selection, turn off Automatic, and select either MobiFone (VN MOBIFONE / 45201) or Vinaphone (VN 02 / 452 02). Do not assume automatic network selection will choose the right one.
Understand the Network Lock limits. ReadyRoam Network Lock blocks data on non-preferred operators. In northern Vietnam, the central highlands, or remote coastal areas where only Viettel has strong signal, your data will be restricted. You can only disable Network Lock by calling Singtel's hotline (+65 6235 1688) — roaming charges apply for that call.
Auto top-up is on by default. If you exhaust a ReadyRoam data bundle, a new bundle of the same size is automatically purchased at the same rate. The validity period does not extend. If you have used 4 GB in five days and run out, you will be charged for another 4 GB automatically.
Calls and texts cost extra. ReadyRoam data plans cover data only. Add the SMSVoiceRoam Asia plan separately if you need to make or receive calls. Check the My Singtel app for current bundled rates.
Keep APN settings handy. If your data does not connect automatically after landing, set the APN to singtel.internet with no username or password. Restart your phone once after network selection.
Singtel roaming in Vietnam makes sense if you are taking a short, primarily urban trip, you only need a small amount of data, and you want to keep your Singapore number active throughout. A 4 GB ReadyRoam plan covers most two-to-three-day business trips to Ho Chi Minh City or Hanoi where you have regular access to hotel Wi-Fi and are not navigating unfamiliar routes or streaming anything.
A dedicated travel eSIM starts making more sense in a few specific situations. If your itinerary includes multiple destinations — say Hanoi, Ha Long Bay, Hoi An, and Ho Chi Minh City — network coverage varies significantly outside major cities. A local eSIM running on Viettel, Vietnam's largest and most geographically extensive operator, gives you better signal in rural areas than either MobiFone or Vinaphone, which are the two networks Singtel has agreements with. If you are spending a week or more in Vietnam and plan to stream, use navigation constantly, or work remotely, a travel eSIM typically offers better data volume at lower total cost. The Dual-SIM advantage also matters here: with an eSIM for local data, you keep your Singtel physical SIM active and reachable on your Singapore number for banking OTPs, calls from home, and work messages — without paying roaming rates on every megabyte.
The practical challenge with Singtel roaming in Vietnam comes down to network selection. Viettel is Vietnam's largest carrier by geographic coverage, ranked third globally for mobile speed by Ookla in 2025, and the operator with the deepest reach into rural areas, islands, and highland destinations. Singtel's ReadyRoam plan does not include Viettel as a preferred network, which means anywhere Viettel dominates — Sapa's mountain valleys, the Mekong Delta, the outer reaches of Phu Quoc — your Network Lock restricts data access.
TurkSIM's Vietnam eSIM operates across the full range of local networks, giving you Viettel's rural reach combined with Vinaphone's increasingly impressive 5G footprint in major cities. VinaPhone was ranked second globally for 5G speed by Ookla in early 2025, which means in Hanoi and Ho Chi Minh City you can expect genuinely fast connections, not just technical coverage. For Singaporeans travelling with an eSIM-capable iPhone or Android, the Dual-SIM advantage is particularly practical: keep your Singtel physical SIM active in slot one for your Singapore number, banking OTPs, and incoming calls from the office, and run the TurkSIM data eSIM in slot two. You maintain full connectivity in both countries without forwarding calls or explaining a new number to anyone.
The use cases where this matters most are the multi-destination itineraries that are common for Singaporean travellers to Vietnam: a week covering Hanoi, an overnight cruise on Ha Long Bay, a domestic flight to Da Nang, and then south to Ho Chi Minh City. Each leg involves different signal conditions and different data needs. A fixed eSIM plan for the whole trip means you activate once and forget about it, rather than managing ReadyRoam bundles per destination segment.
Yes. Vietnam is included in Singtel's Asia ReadyRoam zone. Your plan will connect to either MobiFone (network code 45201) or Vinaphone (network code 452 02). These are the only two preferred networks for Singtel roaming in Vietnam. Viettel and Vietnamobile are not covered, and ReadyRoam Network Lock will block data if your phone connects to them.
For a standard seven-to-ten day trip with moderate data use, the UnlimitedRoam Asia 14 Days plan offers the best value. It includes a 15 GB high-speed threshold before speeds reduce, which is enough for navigation, messaging, and light browsing across a typical itinerary. If you are on prepaid, the hi! Prepaid Asia DataRoam 7-day pack is the practical option. Check current pricing in the My Singtel app before departure.
The most common reason is your phone has connected to Viettel or Vietnamobile instead of a Singtel preferred network. Go to Settings, turn off automatic network selection, and manually choose MobiFone or Vinaphone. If the issue persists, check that your APN is set to singtel.internet and restart your phone. ReadyRoam Network Lock may also be restricting access if you are in an area where no preferred network is available.
ReadyRoam data plans do not include calls or SMS. You need to add the SMSVoiceRoam Asia plan separately to make and receive voice calls using your Singtel number while in Vietnam. Alternatively, most travellers use WhatsApp or Telegram calls over data, which are covered by the data plan and cost nothing extra.
Coverage on Phu Quoc island and Ha Long Bay depends on which operator has signal in those specific areas. In resort zones on Phu Quoc, MobiFone and Vinaphone have reasonable coverage. In more remote parts of the island and on Ha Long Bay's outer islands and water areas, Viettel often has stronger signal. Since Viettel is not a Singtel preferred network, ReadyRoam Network Lock may restrict your data in these locations.
For longer trips or itineraries that include rural areas, a dedicated travel eSIM typically offers better data value than Singtel ReadyRoam. A travel eSIM for Vietnam can provide more data for a similar or lower price, includes access to Viettel's wider network, and avoids the AEST midnight reset issue. For very short urban trips of two or three days with low data needs, Singtel ReadyRoam is a convenient option without the need for a separate eSIM installation.
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