Thai roaming versus a travel eSIM, from the operators' own published rates

What roaming gives you that a travel eSIM cannot

• Your Thai number stays live: it takes calls, receives SMS, and receives your bank's one-time passwords. For many travellers that alone decides it, whatever the price.
• Nothing to install and no eSIM-capable handset needed — you subscribe by USSD code or in the operator's app before you leave, and that is the whole setup.
• Both operators require the Thai SIM to be in normal status and not suspended, but neither asks you to change SIM or change number.
• The higher tiers at both operators bundle voice minutes and SMS, which a data-only eSIM does not have at all.

AIS Ready2Fly, as published

These are the data-only packs, priced excluding 7% VAT exactly as AIS's own page states. AIS also sells Plus, Premium and Beyond tiers that add voice and SMS at higher prices; the source links at the end lead to them.

True and dtac GO Travel, as published

dtac now sits inside True Corporation, and dtac's old roaming page redirects to True's. The page we read carries a last-updated date of 24 August 2026, and every card is labelled as excluding VAT.

What happens when the data runs out

Both operators state the same thing: when the pack's data is used up the line is not cut, it is slowed to 128 Kbps until the pack expires. That speed still carries messaging and, painfully, a map, but not video or photo uploads. The one exception we saw is True's GO Travel Worldwide 15GB for 365 days, where True states the service is suspended automatically rather than slowed.

The timing rules worth knowing before you subscribe

• AIS states the pack activates and bills on first use in the covered countries within 60 days of your set start time. If it goes unused, postpaid is cancelled without charge, while prepaid is charged at purchase and refunded within 15 days after expiry.
• True states that you are charged on subscription and the pack starts once a roaming network is detected, within 30 days of subscribing.
• Both count days as full 24-hour blocks on Thailand time, not destination time, and unused allowance in a daily pack does not carry forward.
• Some of True's upper tiers state that once subscribed the pack cannot be cancelled or changed; read that line before you confirm.

Where a travel eSIM sits differently

• It is bought for one destination or one region, so you are not paying for a zone that spans countries you will not visit.
• It is a separate data line, so your Thai number can stay in the phone and still receive SMS if you leave that line on with data roaming off — the usual way people keep receiving one-time passwords without paying for data.
• It requires an eSIM-capable phone and a profile to install — a step roaming simply does not have.
• Sizes and validities come in finer steps — a small bucket for a three-day trip of maps and chat, a shape the roaming tables rarely carry.

Deciding with your own trip's numbers

1. 1Write down three thingsThe number of days abroad, your real daily usage at home from last month's bill divided by thirty, and whether you must take calls or receive one-time passwords on your Thai number while away.
2. 2If that last answer is yes, weigh convenience before priceA roaming pack with bundled minutes answers that directly, whereas with a data-only eSIM you manage the Thai number separately and accept that calls will not reach you unless voice roaming is on.
3. 3If not, compare per gigabyte and add VAT to both sidesDivide the roaming pack's price by its gigabytes, add 7% VAT, and set that beside the per-gigabyte price of the destination plan you are looking at. Remember that if you travel together and can tether, both options cost per line, not per person.

The limits of this data

• Every price was read on the date stamped, excluding VAT as the operators display it. Both operators change promotions at will and we do not track them in real time; check the operator's page from the links below before subscribing.
• In AIS's own data, the Global 15GB for 15 days returns a VAT-inclusive figure that does not reconcile with its own exclusive figure, so we used only exclusive prices and left that pack out of the table.
• Both operators state coverage as a count rather than a list on the same page. If your destination is a small country or a special territory, confirm the list with the operator first.
• Some AIS tiers are priced differently for Serenade members. The figures here are the standard prices, not the membership ones.
• We sell travel eSIMs, so this page is not a disinterested source. What we do about that is decline to decide for you, keep our own prices out of the comparison tables, and link the operator's source for every figure.

Why an 'unlimited' roaming pack is rarely unlimited

The word 'unlimited' on a subscription page usually means the line will not be cut and you will not be billed extra for the rest of the pack's validity — not that there is no speed ceiling. Almost every operator worldwide writes a separate fair-use clause into its terms document, apart from the pricing card, that sets a volume you can use at full speed before the connection slows past it. The reason is straightforward: while you roam, your home operator pays a foreign partner network per gigabyte carried, so a genuinely uncapped connection barely exists on any roaming product anywhere.

• The fair-use ceiling is almost always written apart from the price table you see when subscribing; you have to open the separate terms and conditions page to find the actual figure.
• The ceiling for roaming use tends to sit lower than the ceiling on a comparable pack used at home, because the cost the operator pays a foreign network is higher than the cost of carrying traffic on its own towers.
• The reduced speed after an unlimited pack's ceiling does not have to match the number that applies to a sized pack; check the figure for the specific product you are about to buy rather than assuming it carries over from another one.
• What an 'unlimited'-named pack usually leaves genuinely open is the number of days or the validity window, not the data volume — that is the part that is truly without limit, not the speed or the amount.
• If your trip depends on heavy use such as work video calls or continuous streaming, the fair-use ceiling matters to you in practice, so ask the operator directly how many gigabytes the specific pack allows before you pay for it.
• The phrase 'fair use' has no single industry-wide definition; each operator sets its own figure and its own way of calculating it. An 'unlimited' pack from one operator therefore does not map directly onto a same-named pack from another, so read each operator's own numbers separately rather than treating the label as a fixed standard.
• Some fair-use clauses skip a fixed gigabyte figure entirely and instead say usage must be 'reasonable' relative to other customers on the same pack, which is far vaguer than a hard number. If you run into wording like that, the safer move is to call or message customer service for a concrete figure before you travel rather than guess from the vague phrase.

Two ways roaming packs bill you, and the activation gap

Once the data you bought runs out, an operator's system is generally built one of two ways. The first slows the connection until the pack expires while keeping basic use alive — the design behind most of the packs tabulated on this page. The second cuts service outright until you buy more or a new pack activates, which is exactly what one pack listed above already does instead of throttling. The distinction matters because it decides whether going over data costs you speed or costs you the connection entirely. Before you travel, check which design the specific pack you are buying uses rather than assuming every pack behaves the same way.

• Most Thai operator roaming packs activate through an app or a USSD code, which you can do before you ever board. If you forget and try to subscribe only after landing, you need hotel or airport Wi-Fi first, because switching on the old line's data roaming to reach the app can already run up charges at the no-pack rate before the pack even starts.
• A travel eSIM's profile is typically installed at home over Wi-Fi ahead of the trip and set to start its validity only on first connection at the destination, so there is no window after landing where you have to hunt for emergency Wi-Fi just to sign up for something.
• Before you leave, open the terms page for the specific pack you plan to buy and look for three things: the full-speed usage ceiling, whether what happens after it is a slowdown or a cutoff, and when the pack's validity actually starts counting. Those three answers cover almost every question that leads to a shock bill.
• The bill-shock risk sits specifically with pay-as-you-go roaming with no pack at all, because it charges for actual use with no fixed upper limit. A travel eSIM is prepaid for a fixed amount: once it is used up it is simply used up, with no unintended figure added afterward.
• If you genuinely have to subscribe only after landing, leave the old line's data roaming off, connect to the airport's Wi-Fi to subscribe in the app, and only switch data back on once you have confirmed the pack is active. That sequence removes almost all of the risk of being billed at the no-pack rate.
• The timing friction differs too. A roaming pack can be subscribed at any point, even by tapping through the app right after you land, because the Thai line is already live. Most travel eSIMs need their profile installed while you still have reliable Wi-Fi before leaving home, since the first-time installation step usually needs a short internet connection of its own. Forget to install one beforehand and arrive with no working Thai line at all, and finding Wi-Fi for that first installation becomes harder than subscribing to a roaming pack through a line that already works.

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