Thailand's mobile market looks like three brands but works like two networks. AIS is the largest operator by reach. True and dtac merged corporately back in March 2023, and it took until 2025 for the two networks to actually finish combining towers and spectrum under a project called 'One Network'. Until then, True and dtac SIMs sat on technically separate infrastructure even though they shared a parent company — which is why older guides describing dtac as a distinct, sometimes patchier network than True may no longer be accurate. Both brands still sell tourist SIMs under their own names at the counter, but the coverage behind them is now the same.
What data actually costs
Pricing for tourist SIMs has been genuinely unstable. Guides from a year or two ago show AIS, True and dtac tourist SIMs tiered anywhere from roughly 250 THB up to 1,699 THB depending on data and validity, with dtac's Happy Tourist SIM usually the cheapest of the three at each duration. A much more recent check found all three carriers had simplified this at the airport counters to a flat 299 THB kit — 30GB over 30 days plus around 100 minutes of calls — though pricing this fluid should be treated as provisional rather than quoted as current fact. On the eSIM side, a Bangkok-specific Holafly plan runs from around $12 for three days up to roughly $74 for 30 days of unlimited data, while a broader 2026 comparison of Thailand eSIMs put a 7-day unlimited plan anywhere from about $10 (Airalo, the cheapest of the group) to around $29 (Holafly, the most expensive), with Holafly working out to the highest daily rate of the set. AT&T sells a flat $12-a-day Daily Pass for Thailand covering unlimited data, calls and texts — a predictable alternative to metered roaming. Verizon reportedly prices its own TravelPass at the same $12 a day, though that allowance is drawn from the existing home plan rather than a separate bucket, and without a day pass at all, roaming can reportedly run to several dollars per megabyte — the reason every guide steers travellers toward a local SIM or eSIM instead.
eSIM or a physical SIM
Per gigabyte, a physical SIM bought at the counter is typically the cheaper of the two — eSIM data tends to carry a small premium. If the goal is squeezing the most data out of the smallest spend, a counter SIM wins on price alone. What it costs you is time: queuing at arrivals, handing over a passport, waiting while it's registered and fitted. An eSIM is bought online before or after landing, arrives as a QR code by email, and can be activated the moment the plane's wheels touch down — there's no airport eSIM counter to queue at, because there's nothing physical to hand over. For a short city trip where the data budget is modest, that convenience is arguably worth the markup. For a longer stay or anyone counting every baht, the counter SIM is the honest answer.
Which network to choose
AIS is repeatedly recommended for anyone leaving Bangkok for islands, national parks or anywhere rural, on the strength of its wider reach. True and dtac's short-validity tourist tiers tend to undercut AIS on price for city-only trips, which is where they're most often recommended instead. Since the underlying networks finished merging in 2025, a True or dtac SIM should now perform similarly to AIS within Bangkok itself — the gap that matters is mainly outside the capital.
Buying at the airport
AIS, dtac and TrueMove H all run 24-hour counters in the arrivals hall at Suvarnabhumi, positioned between immigration and the exit near currency exchange, and True-dtac operates joint counters on Level 1 of Don Mueang's arrivals hall. Nothing needs booking — it's a walk-up purchase at any hour. Long-running traveller forum threads describe a consistent pattern at these counters: staff quote the priciest long-validity package first and only mention the cheaper short tourist tiers if a customer pushes for them. Some travellers who later priced the identical package at a city phone shop — a kiosk at Terminal 21, an AIS store — reported paying a fraction as much. The trade that keeps people buying at the counter anyway is speed: it runs around the clock, staff work in English, and someone else fits and configures the SIM before you've reached the taxi rank. A 7-Eleven near the Airport Rail Link entrance in Suvarnabhumi's basement used to offer a wider range of standard local SIMs at ordinary city prices — a known workaround — but a recent check found it now stocks only the same tourist SIMs at the same price as the arrivals-hall counters, so that loophole may no longer hold. Regular prepaid SIMs used by locals, priced from around 49 baht, are reportedly only sold at city convenience stores and phone shops, not at the airport.
Does your phone support eSIM
Every iPhone from the XR and XS generation onward — the whole XR/XS through 17 lineup, plus the SE 2nd and 3rd generation and iPhone Air — supports eSIM, with one catch: iPhones sold in mainland China generally don't, and only some Hong Kong and Macao units do. On Android, eSIM support generally starts with the Samsung Galaxy S20 series, and Google Pixels have supported it as standard since the Pixel 2 in 2017, with a few regional exceptions on the Pixel 3. Worth checking before buying — an eSIM plan is non-refundable once it's tied to a device that can't use it.
Passport and registration paperwork
Thailand's regulator, the NBTC, requires every SIM — physical or eSIM — to be registered against a passport at the point of sale. That rule has been in motion for over a year: a biometric registration overhaul was approved in principle in January 2025, and further changes around January 2026 reportedly opened up alternative ID documents for people without a passport, alongside broader compliance rules aimed at telecom fraud. None of this changes what a tourist needs to do in practice — bring a passport — but it's worth expecting the exact paperwork at the counter to have shifted slightly since any given guide was written.
