Verizon, AT&T, T-Mobile in Thailand & Vietnam: Roaming Cost

Short answer: Verizon and AT&T both charge $12 for each 24-hour period you use your phone in Thailand or Vietnam, T-Mobile includes a limited amount of data on most postpaid plans, and none of the three gives you full-speed data without a cap. The expensive surprise is not the headline price. It is that a “day” starts when your phone first touches a network, and background data can start it for you.

Everything below was read from the carriers’ own pages on 7 November 2026. Roaming terms change, so check the linked page before you travel. We sell eSIMs for Thailand and Vietnam, which is why there is a comparison with our own prices further down; the carrier figures are quoted as the carriers publish them.

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Verizon, AT&T and T-Mobile side by side

Thailand and Vietnam are both covered by all three carriers, on the same terms in each country.

	Verizon TravelPass	AT&T International Day Pass	T-Mobile (postpaid plans)
Cost in Thailand and Vietnam	$12 per day + taxes	$12 per day (first line), $6 per extra line	Included on most plans; passes from $10
High-speed data	5GB per 24-hour session	Not stated as a number on the pages we read; speed “varies by destination”	5GB, 15GB or 30GB depending on plan
After the allowance	Unlimited at 3G speeds for the rest of the session	Not stated	256kbps (about 128kbps standard speed in the fine print)
Calls and texts	Unlimited talk and text	Unlimited text and calls with the plan	Texts unlimited; calls $0.50/min
How it starts	First use in the country	First use in the country	Automatic on a qualifying plan

Sources: Verizon TravelPass FAQs and country list; AT&T Day Pass terms and pay-per-use rates; T-Mobile’s Thailand and Vietnam pages. All read 7 November 2026.

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Verizon TravelPass: $12 a day, 5GB of fast data, then 3G speeds

Thailand and Vietnam are on Verizon’s TravelPass list at $12 per day plus taxes and fees, and the charge only applies on days you use the phone abroad. Verizon’s page for the country list was read on 7 November 2026.

• What you get: unlimited talk, text and data, but only the first 5GB of each session is high speed. Verizon’s FAQ says that afterwards you get “unlimited data at 3G speeds for the remainder of your TravelPass session” (Verizon FAQ, 7 November 2026).
• How a day works: a session starts automatically on first use in a TravelPass country, whether a call, a text or data, and lasts 24 hours from that moment (Verizon FAQ). Crossing midnight does not start a new one.
• Background data counts. The same FAQ lists app content refreshing, email syncing and device or app software updates as things that can start a session once data or data roaming is on.
• Phone setup: you must turn on cellular data or data roaming when you arrive for TravelPass to work. Verizon’s roaming pay-as-you-go rate if you skip the pass is $2.05 per MB for data and $1.79 per minute for calls (Verizon country page, 7 November 2026).
• Activation: if TravelPass is not already on your line, Verizon’s page says to text TRAVEL to 4004.

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AT&T International Day Pass: $12 a day, the second line is $6

AT&T charges $12 for each 24-hour period of use in a Day Pass country, and its terms say the fee “covers additional data, calls, and text messages for 24 hours from the initial use” (AT&T terms, 7 November 2026). Thailand, Vietnam and Laos all appear in AT&T’s list of destinations with data coverage (AT&T pay-per-use rates, 7 November 2026).

• Added lines: one line pays $12, and each additional line on the same account used on the same calendar day pays $6. AT&T defines that date by “your local U.S. time zone, not the Destination visited”, and the line charged $12 is not necessarily the one used first.
• What does not start it: received text messages are rated as domestic and do not trigger a daily fee, while subsequent 24-hour periods of use charge another fee.
• The cap: there is a maximum of 10 daily fees per line, per monthly bill cycle, for land destinations. That caps one phone at $120 in a cycle (AT&T terms).
• Data speed: the AT&T pages we read say you keep the high-speed data from your home plan when Day Pass is added to an unlimited plan, and that “coverage and data speed vary by destination”. We found no numeric fair-use cap for Thailand or Vietnam on them, so we do not give one.
• Without the pass: pay-per-use data is $2.05 per MB on land, $1 per text and $4 per minute for calls in countries other than Canada and Mexico (AT&T pay-per-use rates, 7 November 2026).

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T-Mobile: included data, then 256kbps

On most T-Mobile postpaid plans, Thailand and Vietnam roaming is included with a high-speed allowance, then data drops to 256kbps. T-Mobile’s Thailand page shows these cards (read 7 November 2026):

Plan	High-speed data in Thailand	Then	Text	Calls
Better Value	30GB	256kbps	Unlimited	$0.50/min
Experience Beyond, Go5G Next	15GB	256kbps	Unlimited	$0.50/min
Experience More, Go5G Plus, MAX, One Plus	5GB	256kbps	Unlimited	$0.50/min
Go5G, Magenta, One	Unlimited data at 256kbps		Unlimited	$0.50/min
Other T-Mobile plans	$1.00 per MB		Unlimited	$0.50/min

We read the full set of cards on the Thailand page. The Vietnam page showed the same Better Value and Experience Beyond cards and the same dialling note, but we did not capture its remaining cards, so check your own plan there.

Fine print that matters for a long trip: T-Mobile’s terms say this is not for extended international use, that you must live in the US with primary usage on the US network, and that service may be restricted for significant roaming. Standard speeds are about 128kbps (T-Mobile roaming terms, 7 November 2026).

If your allowance runs out: T-Mobile sells International Passes: $10 for 2GB and calls for up to 24 hours, $50 for 15GB for up to 10 days, and $75 for 30GB for up to 30 days. One pass is active at a time, and a new pass ends the benefits of the prior one (T-Mobile International Pass, 7 November 2026).

Prepaid is different. T-Mobile’s terms point prepaid customers to a separate “Pay in Advance” page that we did not read, so none of the above applies to prepaid lines.

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What a trip costs: roaming against a travel eSIM

For a one-week trip, the two day-pass carriers cost about $84 in daily fees before taxes, T-Mobile costs $0 extra if your plan includes the data, and a Thailand eSIM from us is $8.90. The calculation below is the daily fee multiplied by the days you use the phone, with no taxes and fees.

Trip	Verizon ($12/day)	AT&T ($12/day)	T-Mobile	Our eSIM
7 days, phone used daily	$84	$84	Included on most plans (30GB, 15GB or 5GB high-speed)	Thailand 7 days $8.90; Vietnam 7 days (35GB) $9.90
10 days, phone used daily	$120	$120 (the 10-fee cap)	Included, or $50 for a 15GB, 10-day pass	Thailand 10 days $11.90

eSIM prices: Thailand and Vietnam plan prices from our catalogue, 7 November 2026. The Thailand 7-day plan is 35GB at full speed, then 1Mbps minimum; the 10-day plan is unlimited at full speed as a limited-time promotion from the network.

Be fair about what you give up and gain:

• Keep your number. Roaming keeps your US number for calls and texts. A travel eSIM is a data line; the Thailand plans can receive calls and SMS but not make them, and Vietnam depends on the plan. With a dual-SIM phone you keep your US SIM for banking codes and run the eSIM for data.
• Against T-Mobile, the money argument disappears. If your plan includes 30GB, an eSIM does not save you anything. What it can add is higher speed after the allowance, since T-Mobile drops to 256kbps.
• Check your phone first. An eSIM needs an unlocked, eSIM-capable phone. Our Thailand eSIM vs physical SIM and Vietnam eSIM vs physical SIM guides compare the local options, and the Vietnam eSIM guide covers installation. If you are visiting more than one country, see one eSIM across Thailand, Vietnam and Cambodia.

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How to avoid a surprise bill

The safest rule is to decide before landing whether you want the pass, and to turn data roaming off if you do not. Both carriers say background activity can start a paid day, so a phone left on in a hotel room can cost $12 without you opening an app.

1. Check your plan before you fly. For T-Mobile, log in and look at the international benefits for your plan. For Verizon, confirm TravelPass is on your line; for AT&T, confirm Day Pass is added.
2. Know when your 24 hours start. First use starts the clock, including a received call on Verizon. A received text does not start AT&T’s.
3. Switch off cellular data or data roaming when you want Wi-Fi only, and turn off app refresh and automatic updates.
4. If you travel with others, AT&T’s $6 additional-line rate only applies when the lines are charged on the same U.S. calendar date.

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What this page does not cover

We cover the three national US postpaid carriers: Verizon, AT&T and T-Mobile. We do not cover prepaid brands such as Mint, Visible or Cricket, business plans, or other countries’ carriers, whose terms differ. If you are on one of those, read your own carrier’s destination page and compare the daily or per-gigabyte price with a travel eSIM yourself.