Source-backed analysis9
Review basis
Research-based review: the AppDuo Editorial Team compiled it from official pages, documentation, app stores, press and user feedback, without hands-on testing. Every claim links to a source with the date it was checked.
9 reference sourcesInformation updated Nov 12, 2026
How we review
Viettel Tammi Review
Viettel's free super app: calls, chat, meetings and digital services
By AppDuo Editorial Team · Fact-checked
- iOS
- Android
- Web
On this page
Decide at a glance
Our verdict
Tammi suits Viettel subscribers who want calls, chat, plan management and bill payment in one free app. On the other hand, it is very new, store ratings sit around 3.1–3.2 out of 5, and no full privacy policy was available to check.
Best for: Viettel subscribers who want plan management, top-ups and utility bills in one app
Skip it if: People who need a complete English interface: in English the app shows only 3 tabs (per Viettel's reply on Google Play)
Pros
- Free to download; Viettel subscribers pay no data charges for calls and messages in the app
- Nearly 50 utilities in one app: calls, messaging, meetings, Viettel service management, shopping, travel, healthcare
- AI assistant inside the chat window, plus Tammi OA verified channels for businesses and agencies
Cons
- Low store ratings: 3.1/5 on the App Store (about 19,300 ratings) and 3.2/5 on Google Play (about 30,900)
- The English version is incomplete: per Viettel's reply on Google Play, it shows only the Chat, Calls and Personal tabs
All pros and cons · Who is it for?
More pros
- Phone-number and OTP verification, optional VNeID linking, end-to-end encryption for supported communication types
- Free online meetings for up to 100 connection points and 120 minutes per session
More cons
- No full privacy policy could be opened; data handling rests mostly on the developer's own declarations
- Growth figures (20 million users, DAU/MAU near 30%) come from Viettel itself; no independent verification was found
Best for
- People who need free online meetings for larger groups (up to 100 connection points)
Experience & key features
Viettel Tammi is a Viettel app; the Google Play publisher is listed as Viettel Telecom. The App Store description splits it into five areas: telecom, services, household utilities, shopping and entertainment, and calls, chat and meetings. Tammi was introduced at MWC Barcelona in March 2026 and entered internal testing in June 2026; the App Store lists a release date of 15 Apr 2026. Press reports put the official launch less than 3 months before 27 Oct 2026.
Key features
Viettel says the app offers calls, messaging, online meetings, an AI assistant in the chat window, and Tammi OA for businesses and agencies to run official channels. Đại biểu Nhân dân reports that Tammi users can call ordinary phone numbers and receive calls from them. VOV counts nearly 50 utilities, from Viettel service management to shopping, travel and healthcare. Accounts are verified by phone number and OTP; a web version runs at tammi.vn.
Pricing and value
The app is free. Viettel says its subscribers use Tammi without data charges and get free online meetings for up to 100 connection points and 120 minutes per session, plus 5 GB of Viettel Cloud. Since 13 Oct 2026 Viettel has sold four 5GTammi data packs only in the app, from 9,000 VND for 6 hours to 60,000 VND for 7 days. These are carrier packages, not paid tiers of Tammi.
More analysis
User ratings
Ratings are fairly low: 3.1/5 on the Vietnam App Store and 3.2/5 on Google Play. On Google Play, several foreign users complain that the English version lacks sections or hides their plan details. Viettel replied publicly that in English the app currently shows three tabs and the rest are still being finished. These are individual opinions, not representative of all users.
Who it fits
Tammi fits Viettel subscribers best because many benefits are tied to Viettel numbers, although Viettel says about 10% of users are on other carriers. If you mainly need a messenger your contacts already use, compare Zalo or Telegram, and read each app's data policy before switching.
Screenshots
Plans & pricing
Prices last verified Nov 12, 2026
Tammi
PersonalFree
Free to download and use. Viettel subscribers are not charged mobile data for calls and messages through Tammi. Online meetings are free for up to 100 connection points and 120 minutes per session. 5 GB of free Viettel Cloud storage.
- Free plan limits
- Per Viettel (via Báo Lào Cai): free online meetings up to 100 connection points and 120 minutes per session; 5 GB free Viettel Cloud storage.
- Free trial
- No free trial
Cancellation & refunds
The app is free, so there is nothing to refund. The 5GTammi data packs are Viettel carrier packages sold through the app rather than Tammi plans; no refund policy for them appears in the sources opened.
Privacy
In its self-declared Google Play data-safety section, the developer states that no data is shared with third parties, data is encrypted in transit and users can request deletion. Viettel says accounts are verified by phone number and OTP, can be linked to VNeID, must be re-verified after a phone change, and that supported communication types use end-to-end encryption (E2EE). AppDuo could not open a full privacy policy because tammi.vn shows only a login screen.
Viettel Tammi alternatives
7.3/10Telegram
Cross-platform cloud messaging with 200,000-member groups, channels and bots
7.1/10Messenger
Meta's chat and group video app, with end-to-end encryption by default for personal chats
Controversies & incidents
Issues documented by the press, regulators, courts or the vendor itself. Every item is sourced; unproven claims are labelled as allegations. Last researched: Nov 12, 2026
No significant controversies or incidents found in the sources we checked.
Frequently asked questions
Is Viettel Tammi free?
Yes. The app is free on the App Store and Google Play. The 5GTammi data packs are separate Viettel carrier packages.
Can subscribers of other carriers use Tammi?
Yes. Viettel says about 10% of users are VinaPhone, MobiFone and other carriers' subscribers. The free-data benefit applies to Viettel subscribers only.
Does Tammi use end-to-end encryption?
Per Viettel, E2EE applies to the communication types that support it; the sources opened do not specify which.
Is Tammi available in English?
There is an English option, but per Viettel's Google Play reply it currently shows only three tabs: Chat, Calls and Personal.
Review evidence & sources9
Scores
- Ease of use
- 6.0
- Features
- 7.0
- Value for money
- 8.0
- Performance
- 6.0
- Support
- 6.0
- Privacy & security
- 6.5
Why this score
The App Store describes a simplified interface in Vietnamese, English and Lao. But Viettel says the English version has only 3 tabs, several foreign users complain about it on Google Play, and 3.1–3.2/5 ratings point to an uneven experience.
Why this score
Nearly 50 utilities: calls, messaging, meetings, app-to-phone calling, an in-chat AI assistant, bill payment and Tammi OA. Broad, though much of it is tied to the Viettel ecosystem.
Why this score
The app is free, Viettel subscribers pay no data for calls and messages, and meetings plus 5 GB of Viettel Cloud cost nothing. The 5GTammi data packs (9,000–60,000 VND) are Viettel carrier packages, not paid tiers of the app.
Why this score
No independent measurements. Nearly every App Store update, including 1.1.51 on 2 Nov 2026, lists "improved call quality". Low store ratings and recent reviews complaining about stability keep this score middling.
Why this score
Viettel publicly answers Google Play reviews and points users to in-app chat, the Viettel Tammi fan page or viettel.vn. No dedicated help centre could be opened, and one foreign user reports the hotline had no English, so there is no basis for a higher score.
Why this score
Per the self-declared Google Play section: no third-party sharing, encryption in transit, deletion on request. Viettel cites OTP verification, VNeID linking and end-to-end encryption. The full policy could not be checked; a search on 12 Nov 2026 found no incident reported by reputable press.
What users say
- App Store (Việt Nam)3.1/5 · 19,268
- Google Play3.2/5 · 30,900
Sources
- Vendor-providedTammi Web (official)Nov 12, 2026
- storeApp Store listing (Vietnam)Nov 12, 2026
- storeGoogle Play listingNov 12, 2026
- pressVOV (2026-10-14)Nov 12, 2026
- pressBáo Lào Cai (2026-10-27)Nov 12, 2026
- pressVnReview (2026-10-27)Nov 12, 2026
- Vendor-providedViettel Telecom website (lists Tammi products)Nov 12, 2026
- pressTuổi Trẻ topic page (article of 2026-10-27)Nov 12, 2026
- pressĐại biểu Nhân dân (2026-08-20)Nov 12, 2026
Specs & compatibility
Change history
- Feature.iOS version 1.1.51 improves call quality.
- Company.Viettel announces Tammi has reached 20 million users less than 3 months after official launch.
- Feature.Viettel starts selling four 5GTammi data packs, available only through the Tammi app.
Full change history (6)
- Company.Đại biểu Nhân dân reports that Tammi has passed 5 million users.
- Launch.Release date listed on the Vietnam App Store.
- Update.Viettel introduces Tammi at MWC Barcelona.
About the author
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