Where the code Big90 comes from
Plan codes in Vietnam are how carriers sell prepaid bundles to their own subscribers. A code like Big90 is quoted exactly as the carrier sells it, and it sits in the catalogue of Vietnamese mobile plans alongside dozens of other codes — daily data add-ons, monthly voice bundles, social-only packages. These are domestic products. They are priced in dong, tied to a Vietnamese SIM, and topped up through the carrier's own channels.
That is the whole of it. Big90 is not a travel product, not an eSIM brand, and not something a visitor buys at a Vietnamese airport counter.
Why travellers keep searching for it
Two things happen. First, plan codes circulate in forums and group chats, stripped of context, and they look like product names. Second, some travellers land in Vietnam, buy a local SIM, and are offered a menu of codes at the counter — Big90 among them. If you already hold a Vietnamese SIM, a code like this may be relevant to you. If you do not, it is not.
For a visitor, the practical question is not which code but which product type. A Vietnamese prepaid SIM requires a passport registration, a shop visit or an airport queue, and a physical SIM swap that costs you your home number for the duration of the trip. A travel eSIM skips all three.
eSIM or local SIM: the decision
| Vietnam eSIM (bought before you fly) | Local Vietnamese SIM (bought on arrival) | |
|---|---|---|
| When you can set it up | At home, on your own wi-fi | After landing, in a queue |
| Passport registration | Not required | Required |
| Keeps your home number active | Yes, dual-SIM | No, you swap the card |
| Plan codes like Big90 apply | No | Yes, if you want a domestic bundle |
| Best for | Trips under a month, most travellers | Long stays, residents, heavy local calling |
If your trip is a holiday — a week, two weeks, a month — the eSIM column is the one that applies to you. The plan-code column is for people who live in Vietnam or stay long enough to justify a local number.
What to buy instead
The VietSIM store sells prepaid Vietnam eSIM plans: you choose a data allowance and a validity window, pay in USD, and receive a QR code by email. You install it before you fly. It activates when it connects to a Vietnamese network on arrival.
Buy the Vietnam eSIM in the store — pick the plan that matches your trip length, not the biggest number on the page.
A few things worth knowing before you choose:
- Installation is a home job. Do it on your own wi-fi, days before departure, not in the arrivals hall. Step-by-step instructions live in the Vietnam eSIM activation guide.
- Check your phone first. Most modern handsets support eSIM, but the list is not universal. The Vietnam eSIM for iPhone and Vietnam eSIM for Android guides cover compatibility and dual-SIM behaviour.
- "Unlimited" deserves a read. If a plan says unlimited, find out what that means in practice — the Vietnam eSIM unlimited guide explains the throttling and fair-use conventions.
- Hotspotting works, but it costs data. If you plan to tether a laptop or a second phone, read the Vietnam eSIM hotspot guide before you pick a size.
If you already hold a Vietnamese SIM
Then a code like Big90 may be exactly what you are looking for — but not from this site. VietSIM is a prepaid eSIM store and an information catalogue; it does not run a carrier top-up service. Domestic top-ups are handled by the carrier whose plan you hold, through that carrier's own app, USSD menu or agent network.
The catalogue pages on this site quote plan codes exactly as they are sold so that Vietnamese subscribers can compare them. They are informational. They are not a checkout.
What the code does not tell you
A plan code is a label, not a specification. It does not tell you the network, the validity window, the data allowance, or how activation works — those come from the product record for that specific plan. Anyone quoting a code without those details is quoting half a product.
The same discipline applies to travel eSIMs. Before you buy, check three things on the product page: the network the plan runs on, the validity window, and how activation is triggered. Those three facts are what you are actually paying for.
The short version
Big90 is a domestic Vietnamese carrier plan code. Travellers do not buy it, cannot activate it on a foreign SIM, and gain nothing by hunting for it. Buy a Vietnam eSIM before you fly, install it at home, and land connected.
If you have already ordered and lost the email with your installation link, the help centre is where to start — order links are sent by email and are not retrievable from a public page.