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Bulk SMS in Vietnam: Brandname Registration and Decree 91

Bulk SMS Vietnam guide: brandname registration, Decree 91/2020 rules on consent, [QC] marking and 07:00 to 22:00 hours, operators and Vietnamese Unicode.

Updated 10 min read

By OmniChannels.ai Editorial Team · Reviewed by BroadNet Messaging Solutions Team

SMS & OTP

Short answer

To send bulk SMS in Vietnam, register a brandname (a sender name of up to 11 characters) through the national system run by the Authority of Information Security, send advertising only to people who consented, start every advertisement with [QC] or [AD], and send it between 07:00 and 22:00. Keep OTPs and alerts separate from promotions, and expect Vietnamese text with tone marks to be sent as Unicode.

On this page
  1. What rules apply to bulk SMS in Vietnam?
  2. What does Decree 91/2020 require for advertising SMS?
  3. How does brandname registration work?
  4. Which operators carry SMS in Vietnam?
  5. How should you separate OTP and advertising traffic?
  6. How does Vietnamese text affect SMS length?
  7. When should you send?
  8. A worked example: a Hue coffee chain
  9. What are the common mistakes?
  10. How OmniChannels.ai helps

Key takeaways

  • Decree 91/2020/ND-CP is the core rule: advertising SMS may only be sent after a brandname has been granted, only to people who gave prior consent, and not to numbers on the national Do Not Call list.
  • A brandname has up to 11 characters (Latin letters, digits, hyphen, underscore, full stop or space, never digits only); the decree makes a granted brandname valid for 3 years, and phone numbers cannot be used as the sender of advertising.
  • Advertising messages must be marked [QC] or [AD] at the start, sent between 07:00 and 22:00 and capped at 3 per number in 24 hours unless the user agrees otherwise; OTPs and service alerts are not advertising.
  • Three mobile networks appear in our coverage data with direct routes: Viettel (452-04), Vinaphone (452-02) and Mobifone (452-01); our published sender ID lead time is 7 to 14 business days.
  • Vietnamese with diacritics is Unicode: 70 characters in one message and 67 per part when split, while unaccented text fits GSM-7 at 160 and 153, which is cheaper but harder to read.

This guide is for marketing, e-commerce, fintech and operations teams that want to send business SMS to mobile numbers in Vietnam: OTPs, order alerts, reminders and promotions. It explains how the brandname system works, what Decree 91/2020 requires for advertising messages, which networks carry your traffic and how Vietnamese text changes message length. It is a practical overview, not legal advice; confirm requirements with Vietnamese counsel and your provider before launch.

What rules apply to bulk SMS in Vietnam?

The main rule is Decree 91/2020/ND-CP on fighting spam messages, spam emails and spam calls, supported by Vietnam's personal data law. The decree treats advertising messages sent without prior consent, or in breach of its rules, as spam.

Layer What it covers Where to check
Decree 91/2020/ND-CP Brandnames, consent, Do Not Call list, [QC] marking, sending hours, daily cap, opt-out Decree text
Authority of Information Security (AIS) Runs the brandname and Do Not Call systems ais.gov.vn
Law on Personal Data Protection 2025 Consent and rights over personal data, in force from 1 January 2026 Overview
Operators (Viettel, Vinaphone, Mobifone) Routes, filtering and onboarding of senders Your provider

Our regulation data lists AIS as the regulator and records that registration is required through the national brandname system under Decree 91/2020/ND-CP. One point of terminology: the decree names the Ministry of Information and Communications, with the Authority of Information Security as its unit. That ministry was dissolved on 18 February 2025 and its functions moved to the Ministry of Science and Technology and the Ministry of Culture, Sports and Tourism, so confirm the current ministry and portal with the authority or your provider rather than relying on older names.

What does Decree 91/2020 require for advertising SMS?

It sets six practical rules for advertising messages. Anything that promotes a product, offer or brand falls under them; a one-time passcode does not.

  1. Prior consent. Advertising may only go to people who agreed beforehand. The decree lists accepted ways to register consent, including a call centre, a website form or a support tool.
  2. No Do Not Call numbers. Advertisers must check the national Do Not Call list and may not message numbers on it.
  3. A granted brandname. Advertising messages may only be sent after a brandname has been granted, and phone numbers may not be used for this.
  4. The [QC] mark. Every advertising message must be marked [QC] or [AD], and the mark must be at the top of the content.
  5. Hours and frequency. Messages may be sent from 07:00 to 22:00 daily, and no more than 3 advertising messages may go to one number in 24 hours, unless the user agrees otherwise.
  6. Immediate stop on opt-out. After an opt-out request the sender must stop at once and send a single confirmation without advertising content.

Our regulation data agrees with the 07:00 to 22:00 window and adds two operating rules: opt-in must be verifiable, and opt-out is handled with a STOP keyword and suppression applied automatically. For the personal data law, which applies from 1 January 2026, treat consent as the safe basis for marketing, keep records of when and how each number agreed, and ask local counsel about edge cases such as small-business exemptions.

For consent wording, our opt-in consent generator drafts a text, and the guide to opt-in consent across channels explains how to record it.

How does brandname registration work?

A brandname is Vietnam's term for an alphanumeric sender ID: up to 11 characters, using Latin letters, digits, hyphen, underscore, full stop or space, and never digits only. In the decree, a granted brandname is unique and valid for 3 years, and using someone else's brandname without permission is prohibited.

Organisations apply with a certified copy of their establishment decision or business registration certificate plus a written declaration; individuals use a certified ID or passport. The decree allows applications by post or online through the authority's portal, and it gives the authority one working day to decide once it has a complete application.

Our published lead time for Vietnam is 7 to 14 business days. Treat it as a typical range, not a guarantee.

Step What to do
1. Classify Decide which traffic is advertising and which is service or OTP, and plan sender names for each
2. Choose names Use your registered business or product name; avoid names that imitate banks, operators or government bodies
3. Prepare documents Business registration papers and an authorisation letter naming the brandname and your provider
4. Submit Your provider files the registration and tracks each approval
5. Test Send an OTP and a [QC] promotion to Viettel, Vinaphone and Mobifone handsets

Our sender ID letter generator drafts the authorisation letter, and the Vietnam sender ID page shows the current data. If you want us to prepare and file the registration, see registrations; approval decisions stay with the authority and operators. For background on formats, read SMS sender ID types explained.

Which operators carry SMS in Vietnam?

Three mobile networks appear in our coverage data, each with a direct route.

Operator MCC-MNC
Viettel 452-04
Vinaphone 452-02
Mobifone 452-01

Read delivery reports per operator rather than a blended figure, because a healthy total can hide one weak network. The guide to improving SMS delivery rates shows how to diagnose it.

How should you separate OTP and advertising traffic?

Keep OTPs, order alerts and other service messages apart from advertising, with their own sender name and route. Advertising carries legal duties (consent, [QC], hours, cap, Do Not Call checks) that a login code should never inherit.

Traffic Example Practice
OTP / service Login code, payment confirmation, delivery alert No promotion inside; own sender name; any hour
Advertising Sale, new product, loyalty offer Consented numbers only; [QC] at the start; 07:00 to 22:00; Do Not Call check
Mixed "Your parcel shipped. Get 10% off next order" Avoid; the offer makes it advertising

For OTP design and security, see our OTP authentication messages guide.

How does Vietnamese text affect SMS length?

Vietnamese with tone marks is sent as Unicode, which holds 70 characters in one message and 67 per part when split. Text written without diacritics uses the GSM 7-bit alphabet, which holds 160 characters and 153 per part. Many Vietnamese letters with stacked marks, such as ế, ặ and ữ, are not in the GSM alphabet, so a single one switches the whole message to Unicode. See GSM-7, UCS-2 and concatenated SMS.

These examples were counted against the limits (Cafe Hue is a synthetic brand):

Message Encoding Characters Parts
Ma OTP cua ban la 482913. Co hieu luc 5 phut. Khong chia se ma voi bat ky ai. Cafe Hue GSM-7 86 1
Mã OTP của bạn là 482913. Có hiệu lực 5 phút. Không chia sẻ mã với bất kỳ ai. Cafe Hue Unicode 86 2
[QC] Cafe Hue: Mua 2 tang 1 cuoi tuan nay. Chi tiet: cafehue.example/km Tu choi: cafehue.example/tc GSM-7 101 1
[QC] Cafe Huế: Mua 2 tặng 1 cuối tuần này. Chi tiết: cafehue.example/km Từ chối: cafehue.example/tc Unicode 99 2

In GSM-7 the square brackets of [QC] are extension characters that count as two each, which is why the third row is 101 septets for 97 visible characters. The accented versions read better but cost an extra part. Decide per message type: a clear accented OTP in two parts may be worth it, while a long promotion may be better rewritten shorter. Check final copy in the SMS character counter, and for other scripts see SMS character limits and Unicode.

When should you send?

Send advertising between 07:00 and 22:00 Vietnam time (UTC+7) and keep to three advertising messages per number in 24 hours. Both limits come from Decree 91/2020 and can be varied only if the user agrees. OTPs and alerts can go at any hour. The send time planner helps with scheduling, and SMS marketing rules by country compares hours across markets.

A worked example: a Hue coffee chain

"Cafe Hue" (synthetic) has 30 shops and wants OTPs for its loyalty app, order alerts and a weekly offer.

  • It registers one brandname for service messages and one for advertising, and tests both on Viettel, Vinaphone and Mobifone.
  • It collects consent in the app and at the till, storing the wording, time and number, with a clear way to decline.
  • OTPs and alerts are sent without diacritics at 160 septets or fewer, after a test showed customers understood them.
  • The weekly offer starts with [QC], goes out at 10:00, never more than three times in 24 hours, and is checked against the suppression list and the Do Not Call list.
  • Opt-outs from the link feed one suppression list shared with other channels.

What are the common mistakes?

  • No [QC] mark. The decree requires it on every advertisement.
  • Sending from a phone number. Advertising must use a granted brandname.
  • Skipping the Do Not Call check. Consent does not remove the duty to check the list.
  • Promotion inside an OTP. It turns a service message into advertising.
  • Accidental Unicode. One accented letter or smart quote doubles the cost of a long message.
  • Treating lead times as promises. Plan buffer beyond 7 to 14 business days.

How OmniChannels.ai helps

OmniChannels.ai is powered by BroadNet, which has direct routes to Viettel, Vinaphone and Mobifone in our coverage data. We prepare and file brandname registration with you, support Vietnamese and English content, and give you per-operator delivery reports, with SMPP 3.4 for high volume. For indicative list prices, see the Vietnam SMS pricing page, then book a demo. For channel planning beyond SMS, compare WhatsApp, SMS and RCS.

Frequently asked questions

Is bulk SMS legal in Vietnam?

Yes, businesses send OTPs, alerts and advertising by SMS, but advertising is tightly regulated by Decree 91/2020/ND-CP. You need a granted brandname, prior consent from each recipient, a [QC] or [AD] mark, and you must respect the Do Not Call list and the daily sending window. Service and OTP messages are not advertising, though they should stay free of promotions.

What is a brandname in Vietnam?

A brandname is the alphanumeric sender name that shows on the recipient's phone instead of a number. Under Decree 91 it has up to 11 characters from Latin letters, digits and a few symbols, cannot be digits only, and is unique once granted. Advertising messages may only be sent under a granted brandname, not from a phone number.

What time can you send advertising SMS in Vietnam?

Decree 91/2020 allows advertising messages from 07:00 to 22:00 every day unless the user agrees otherwise, and it caps advertising at 3 messages per phone number in 24 hours. Our regulation data records the same window for Vietnam. OTPs and other service messages are not advertising, so they can go at any hour.

What does [QC] mean at the start of an SMS?

QC stands for quang cao, meaning advertisement. Decree 91 requires every advertising message to be marked [QC] or [AD] at the top of its content so recipients can tell it is an advertisement. The brackets are GSM extension characters, so in a GSM-7 message the mark uses 6 of your 160 characters.

Does Vietnamese text need Unicode for SMS?

Vietnamese written with tone marks needs Unicode, because letters such as ế, ặ and ữ are not in the GSM 7-bit alphabet. A Unicode message holds 70 characters, or 67 per part when split. Text without diacritics fits GSM-7 at 160 characters, but many readers find it harder to understand, so test both on your audience.

How long does brandname registration take in Vietnam?

Our published lead time for Vietnam is 7 to 14 business days. That is typical, not a promise. The decree sets a one working day decision period for the authority itself, but a real launch also involves preparing documents and onboarding on each operator route, so build in buffer and let our team file the registration with you.

Sources

  1. Decree No. 91/2020/ND-CP on fighting spam messages, spam emails and spam calls (English translation), LuatVietnam
  2. Authority of Information Security (AIS), Vietnam
  3. Brandname registration portal, Authority of Information Security
  4. Law on Personal Data Protection 2025 (Law No. 91/2025/QH15): overview, Tilleke & Gibbins
  5. 3GPP TS 23.038: Alphabets and language-specific information

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