How to top up your Vietnam eSIM when data runs out
When your Vietnam eSIM data is about to run out, the first step is checking your remaining balance. Use USSD codes, carrier apps, or your phone's settings to see exactly how much is left. Once you know, topping up is straightforward — the easiest method for tourists is through simvietnam.telebox.vn, where you can purchase additional data plans in minutes.
Check how much data you have left
Before you top up, know your remaining data. Each Vietnamese carrier has a USSD code: dial *101# for Viettel, *900# for Vinaphone, or *100# (or *100*1#) for Mobifone. These codes return a balance display on the screen in a few seconds. They work on any phone — no app needed.
You can also check via the account portal of the provider where you purchased the eSIM. Log in with the email used at purchase to see remaining data in GB. Carrier apps (Viettel My Viettel, Vinaphone My VNPT, Mobifone My Mobi) show the same info. On iOS, go to Settings > Cellular > select your eSIM to view data usage, though this may not be real-time — the USSD method is more accurate.
Top up via your provider's account
Log in to the provider's website using the email you used when buying the eSIM. Select a plan that matches your carrier (same carrier — Viettel with Viettel, Vinaphone with Vinaphone, etc.) and a data bucket equal to or larger than your current one. Payment is via card or PayPal, and the top-up is applied within 5 minutes.
For example, if you have a Viettel 5GB/day plan, you can top up with another Viettel 7-day or 15-day plan. The new plan resets your data to the full daily cap, extending your validity. This only works if your original plan is still active — for most carriers, you have up to 72 hours after expiration to top up before the number is released.
Top up directly through the carrier
Carriers offer direct top-up methods, but they are less convenient for tourists. For Viettel, dial *098*PIN# to add credit via a scratch card — but scratch cards are rare for eSIM users and hard to find. Vinaphone has eTopup via website or the *900# menu. Mobifone lets you use *100# then select 'Nap tien'.
These carrier portals often require a Vietnamese ID or local bank account, which most tourists do not have. The provider's top-up method is simpler: no language barrier, no local payment setup, and you can do it entirely online in English.
What happens when data runs out
Outcomes depend on your plan and carrier. For Viettel and Vinaphone 5GB/day plans, hitting the daily cap throttles speed to about 128 kbps — enough for messaging apps and map navigation, but not for video streaming. Mobifone 7GB/day plans have a hard cutoff: data stops completely until the next day or until you top up with an extra plan.
The total data cap (e.g., 35GB for a 7-day plan at 5GB/day) may be reached earlier if you use more than the daily allowance repeatedly. Once the total is used, data stops until you top up with a new plan. After the plan's validity expires, all eSIM services stop entirely; a top-up must include a new validity period to resume.
Tips to avoid running out early
Choose a plan with a higher daily allowance or longer duration than you think you need. For example, a Viettel 7-day plan at $10 gives 5GB/day; if you anticipate heavy usage, consider a 15-day plan ($11) which is cheaper per GB than buying two 7-day plans. Preloading two plans is also effective: activate one immediately, keep the QR code for the second in case of emergency.
Monitor your usage each evening using the USSD codes listed earlier. If you’re staying 15 days or more, a 30-day plan is usually more cost-effective than two shorter ones. Take advantage of hotel Wi-Fi for downloading large files or streaming — this saves your mobile data for navigation and essential on-the-go use.
Top-up not working? Fix it
If a top-up hasn't applied after 5 minutes, restart your phone or toggle airplane mode. This forces the eSIM to reconnect to the network and refresh the data allowance. If that doesn't work, check that the eSIM is still installed and using the same IMSI profile — if you deleted it, the top-up cannot reach the profile and you'll need to buy a new eSIM.
Contact your provider's support with your order ID; they usually resolve issues within one hour during business hours. If the plan expired more than 72 hours ago, the carrier may have released the phone number — in that case, you cannot top up; purchase a new eSIM instead. Also ensure that in your phone's dual-SIM settings, the Vietnamese eSIM is set as the primary mobile data line.
FAQ
Can I top up my Vietnam eSIM online after arriving?
Yes. Log in to the provider’s website using the email you used at purchase, select a plan matching your current carrier, and pay via card or PayPal. The top-up is applied within 5 minutes. You do not need to be at an airport or store.
How do I check how much data I have left on my Viettel eSIM?
Dial *101# on your phone and press call. The response will show your remaining data in MB or GB. Alternatively, use the My Viettel app or the account portal of the provider you bought the eSIM from.
What happens if I don't top up and my data runs out?
For Viettel and Vinaphone 5GB/day plans, speed is throttled to about 128 kbps after the daily cap — still usable for messaging and maps. For Mobifone 7GB/day, data stops completely until the next day or until you top up. Once the plan expires, all services stop until you purchase a new plan.
Can I buy a second eSIM and use both on the same phone?
Yes, most modern phones support dual eSIM. You can keep the first one installed (even if expired) and activate a second eSIM as a separate line. Just make sure the new eSIM is set as the primary data line in your settings.
My top-up was charged but not applied — what do I do?
First, restart your phone or toggle airplane mode. If that doesn't work, contact your provider’s support with the order ID. They can usually apply the top-up manually within an hour during business hours. If the plan expired more than 72 hours ago, the number may be released and you'll need a new eSIM.