business phone · 7 min read
How to Call Vietnam from the US
Dial 011 + 84 + area code (drop leading 0) + local number to call Vietnam from the US. Covers Hanoi, Ho Chi Minh City, mobile prefixes, and 2017 renumbering.
Key facts (as of June 2026): To call Vietnam from the US, dial 011 + 84 + the area code and local number (drop the leading 0). 011 is the US international exit code and 84 is Vietnam’s country code. From a US mobile, press and hold 0 to enter + and dial +84 instead of 011.
To call Vietnam from the US, dial 011 + 84 + area code (drop the leading 0) + local number.
Hanoi example: 011-84-24-XXXX-XXXX (area code 24, formerly 4 before the 2017 reform).
Ho Chi Minh City: 011-84-28-XXXX-XXXX (area code 28, formerly 8).
Vietnamese mobile: 011-84-9XX-XXX-XXXX (10-digit national number minus the leading 0).
Vietnam’s country code is +84. The 011 is the US international exit code. From a US mobile you can substitute + for 011 and dial +84 directly.
How to dial Vietnam from the US
The full dialing sequence from any US phone:
- Dial 011 — the US international exit code. Every US outbound international call starts here. On a US mobile, long-press 0 to enter + as a shorthand.
- Dial 84 — Vietnam’s ITU-assigned country code.
- Dial the area code without its leading 0. Hanoi’s national area code is 024; drop the 0 → dial 24. Ho Chi Minh City is 028; drop the 0 → dial 28.
- Dial the local subscriber number as written.
- Press call.
The full pattern: 011 84 <area code without 0> <local number>.
If you see a Vietnamese number already in international format — for example +84 24 3825 6789 — replace the + with 011 from a landline, or dial it as-is with the + from a mobile.
Vietnamese area codes by major city
Vietnam standardized area codes to a 2–3 digit format in 2017. Older directories still list the pre-reform single-digit codes; those will not connect.
| City | Area code (dial after 84) | Pre-2017 code |
|---|---|---|
| Hanoi | 24 | 4 |
| Ho Chi Minh City | 28 | 8 |
| Đà Nẵng | 236 | 511 |
| Hải Phòng | 225 | 31 |
| Cần Thơ | 292 | 710 |
| Huế | 234 | 54 |
| Nha Trang | 258 | 58 |
| Vũng Tàu | 254 | 64 |
To call a Đà Nẵng landline from the US: 011 84 236 XXXX XXX.
The leading 0 in the national area code (e.g., 0236) is always dropped when dialing internationally. It exists only for domestic calls within Vietnam.
How Vietnamese numbering works — the 2017 mobile renumbering
Before November 2017, Vietnamese mobiles used 11-digit numbers. The first three digits after the trunk prefix 0 formed the operator prefix — for example, 0162 was Viettel, 0120 was Mobifone.
Vietnam’s Ministry of Information and Communications mandated a full conversion to 10-digit numbers. The rule: drop the trunk 0, drop the second digit (always 1 in the old format), keep the rest.
Examples of converted numbers:
| Old (11-digit) | New (10-digit) | Carrier |
|---|---|---|
| 0162 XXX XXXX | 032 XXX XXXX | Viettel |
| 0120 XXX XXXX | 070 XXX XXXX | Mobifone |
| 0121 XXX XXXX | 079 XXX XXXX | Mobifone |
| 0163 XXX XXXX | 033 XXX XXXX | Viettel |
The conversion completed in November 2018. If an old contact’s number stops working, the 11→10 digit conversion is the first thing to check.
Current mobile prefixes (post-2017, after dropping the leading 0 for international dialing): 3x, 5x, 7x, 8x, 9x — all are valid mobile ranges.
Time zones — ICT
Vietnam uses Indochina Time (ICT), UTC+7, year-round. Vietnam observes no daylight saving time.
| US time zone | Offset to ICT |
|---|---|
| Eastern Standard Time (EST, UTC−5) | +12 hours |
| Eastern Daylight Time (EDT, UTC−4) | +11 hours |
| Central Standard Time (CST, UTC−6) | +13 hours |
| Pacific Standard Time (PST, UTC−8) | +15 hours |
| Pacific Daylight Time (PDT, UTC−7) | +14 hours |
ICT is the same offset as Bangkok (Thailand) and Jakarta (Indonesia).
Vietnam’s standard business hours are 8 AM – 5 PM ICT Monday to Friday, with a midday break common in many offices. A 9 AM call to Hanoi from New York (EST) requires you to be at your desk at 9 PM the night before. Plan calls accordingly — early US morning (6–8 AM ET) hits Vietnamese afternoon.
US to Vietnam calling costs
Cost varies significantly by how you call:
US carrier per-minute (no add-on): AT&T and Verizon publish rates of $2–$4 per minute to Vietnam. A 10-minute business call costs $20–$40 at that rate.
US carrier international add-on: Monthly packages ($5–$15) reduce per-minute rates. Still typically $0.20–$0.50/min to Vietnam destinations.
VoIP per-minute: Business VoIP providers including DialPhone charge $0.02–$0.05 per minute to Vietnamese landlines and mobiles. No monthly add-on required.
For US companies with regular Vietnam contact — suppliers, factories, in-country staff — business VoIP is the only sensible option. See DialPhone pricing for current Vietnam rates.
Calling Vietnamese mobile vs landline — and Zalo’s dominance
Vietnamese mobile numbers follow the same international dialing format as landlines: 011 + 84 + number minus leading 0. There is no separate dialing rule for mobile.
You can identify a mobile by its national prefix: anything starting with 03x, 05x, 07x, 08x, or 09x (after the trunk 0) is a mobile. Geographic landlines start with 02x. Pre-2017 numbers starting with 04 or 08 (single-digit area code) are Hanoi and HCMC landlines.
Zalo note: Zalo is Vietnam’s dominant personal messaging platform — roughly 75 million users, the majority of Vietnamese smartphone users. For personal contacts, a Zalo voice or video call over Wi-Fi is free.
For business calls — outbound to Vietnamese suppliers, factories, or distributors — Zalo is not a substitute for a proper phone line. Contacts may not have the app, calls are not CRM-logged, and you cannot present a consistent caller ID. A VoIP business line with a Vietnamese DID is the standard for US importers calling Vietnam regularly.
SMS to Vietnam and the business case
SMS to Vietnam from a US number works through standard international SMS routing. Format: +84 followed by the 9-digit mobile number (leading 0 dropped).
The US-Vietnam business relationship has grown substantially since the 2001 Bilateral Trade Agreement. Vietnam is now a major source for textile, footwear, and electronics manufacturing. Nike and Adidas source significant production there. US importers, quality-control teams, and logistics coordinators routinely need reliable voice and SMS lines into Vietnam.
Vietnamese diaspora in the US (over 2 million people, concentrated in California, Texas, and Virginia) also drives high personal call volume to Vietnam, making consumer-facing VoIP and international add-on plans a common need.
For US businesses with Vietnamese manufacturing partners, a DialPhone business phone plan provides verified caller ID through STIR/SHAKEN attestation on outbound calls. Vietnamese business contacts receiving calls from authenticated US numbers are less likely to screen or reject them. See STIR/SHAKEN explained for how attestation works.
For high-volume inbound from Vietnam — supplier callbacks, factory confirmations — consider a Vietnamese DID so your Vietnamese contacts call a local number. Pair it with DialPhone AI Receptionist to handle after-hours calls across the 11–15 hour time gap automatically.
FAQ
Calling Vietnam from the US — FAQ
What is the country code for Vietnam?
Vietnam's country code is +84. From a US landline or mobile, you reach it by dialing 011 first, giving a full prefix of 011 84.
From a US mobile that supports E.164, you can substitute + for 011, so +84 followed by the Vietnamese number minus its leading 0 works directly.
Do I drop the 0 when calling Vietnam from the US?
Yes. Vietnamese national numbers are written with a leading 0 — for example, 024 3825 6789 for a Hanoi landline or 0912 345 678 for a mobile. That leading 0 is Vietnam's domestic trunk prefix.
When calling from the US, replace it with 011 84, so 024 3825 6789 becomes 011 84 24 3825 6789. Leaving the 0 in is the most common reason a US-to-Vietnam call fails.
Why do some Vietnamese phone numbers have 11 digits?
Before 2017, Vietnamese mobile numbers used an 11-digit format with prefixes starting with 1 (for example 0120, 0121, 0162). Vietnam's Ministry of Information and Communications standardized all mobile numbers to 10 digits between November 2017 and November 2018.
Old 11-digit numbers were converted: the 0 trunk prefix stayed, the second digit 1 was dropped, and the remaining digits shifted. If you have an old contact with an 11-digit Vietnamese number, it likely no longer works and you need the converted 10-digit version.
What are Vietnam's major area codes?
Vietnam standardized its area codes to 2–3 digits in 2017. Key codes (drop the leading 0 when dialing from the US): Hanoi 24, Ho Chi Minh City 28, Đà Nẵng 236, Hải Phòng 225, Cần Thơ 292, Huế 234, Nha Trang 258, Vũng Tàu 254.
Pre-2017 codes (Hanoi was 4, HCMC was 8) appear in older directories and will not connect.
How do I call a Vietnamese mobile from the US?
Vietnamese mobile numbers are 10 digits in national format, starting with 03x, 05x, 07x, 08x, or 09x. Drop the leading 0 and apply the standard pattern: 011 84 + remaining 9 digits.
Example: mobile 0912 345 678 → dial 011 84 912 345 678. The prefix tells you the carrier (Viettel, Mobifone, Vinaphone, etc.) but the dialing format is identical regardless of carrier.
What time zone is Vietnam in?
Vietnam uses Indochina Time (ICT), which is UTC+7 with no daylight saving time. During US Eastern Standard Time (UTC−5), Vietnam is 12 hours ahead — 9 AM EST is 9 PM in Hanoi. During EDT (UTC−4), Vietnam is 11 hours ahead.
For US Pacific Time: add 15 hours (PST) or 14 hours (PDT). Vietnam's business hours are roughly 8 AM–5 PM ICT, which corresponds to 8–9 PM US Eastern the previous evening.
What is the cheapest way to call Vietnam from the US?
VoIP providers are consistently the lowest-cost option, typically $0.02–$0.05 per minute to Vietnamese landlines and mobiles, with no monthly international plan required.
Major US carriers charge $2–$4 per minute without an international add-on; add-on packages reduce that but still cost more than business VoIP per minute. For teams calling Vietnam regularly — US importers, manufacturers, or diaspora with frequent contact — a VoIP business phone plan like DialPhone pays for itself within the first few hours of calls per month.
Does Zalo work for calling Vietnam?
Yes. Zalo is Vietnam's dominant messaging and VoIP app with over 75 million users, mainly in Vietnam. For personal contacts who use smartphones, a Zalo call is free over Wi-Fi or mobile data.
However, Zalo is not a substitute for a business phone number — you cannot present a consistent US or Vietnamese business number, calls are not logged in a CRM, and recipients must also have the app. For business-to-business calls or outbound sales into Vietnam, a VoIP line with a Vietnamese DID is the professional standard.
Related guides
- How to call the UK from the US
- Number porting guide
- STIR/SHAKEN explained
- DialPhone business phone
- DialPhone AI Receptionist
- DialPhone pricing
- Start free trial
Call other countries from the US
Part of the How to Call Internationally from the US hub — exit code 011, country codes, and the per-country mobile rules.
About the author
Growth Operations Lead at DialPhone
Darshan leads Growth Operations at DialPhone, where he owns three interconnected programs: the comparison content operation, the open VoIP Pricing Dataset, and the test-call methodology used to verify every pricing claim published on the site.
His research process starts with hands-on product trials and live vendor quotes — not marketing pages. Pricing figures are cross-checked against actual invoices and re-verified on a rolling quarterly cycle, with the underlying dataset kept public for independent re-verification. That dataset now covers 40+ VoIP and virtual-number providers across the US and Canada market.
Darshan also leads DialPhone's AI receptionist evaluation program, running structured test-call scenarios across English, Spanish, and French to assess transcription accuracy, intent routing, and escalation behavior. Methodology notes and raw scoring are archived in the research section.
For factual corrections or dataset discrepancies, Darshan can be reached at the DialPhone editorial address. Verified corrections are published as errata with a changelog date — no silent edits.