Can I use my own phone, and where do I get a SIM?
Short answer
Yes, if the handset is unlocked — and bring your passport, because every SIM here is registered to a named person.
Two things to settle before you fly
Unlock the handset with your home carrier before boarding — a locked phone cannot take a Thai SIM no matter which one you buy, and sorting it from Bangkok is a much worse afternoon than sorting it at home.
Then remember the passport. Carriers must register every SIM against the buyer's name and passport number, so the document is part of the purchase rather than an optional ID check.
Where to buy, and which
For a week or less, the airport counters are the tourism authority's own recommendation — convenience beats price on a short trip. For longer stays, the carrier shops in city malls carry a wider, cheaper range of plans.
Three networks cover the country: AIS, DTAC and TrueMove H, all selling pay-as-you-go data by the day, week or month. Coverage reaches everywhere except the remotest islands and mountains.
Topping up, and the free layer underneath
Credit is added at any 7-Eleven, at carrier shops, or at the Boonterm kiosks that stand nationwide. Tourist prepaid SIMs typically carry 30 days of validity after each top-up, so a two-week trip needs one purchase and no thought.
Free wifi fills the gaps: hotels, restaurants and cafés all provide it as standard. At Suvarnabhumi there is airport wifi for up to two hours a day, plus free internet kiosks in fifteen-minute sessions — enough to land, message home and order a ride before the SIM is even open.
Good to know
- Unlock the handset before you fly — it cannot be fixed easily on arrival
- The passport is required at purchase; SIMs are registered by name
- Top up at any 7-Eleven; prepaid validity is usually 30 days
Yes. A prepaid eSIM is usually far cheaper than roaming — but it gives you data only, not a Japanese number.
Yes, but decide how before you fly. A local SIM has to be registered against your passport, and a number of services you use daily will not load.
Buy a prepaid SIM on arrival with your passport — it is cheap, the coverage is good, and a local number is what makes the ride-hailing apps work.
Yes, and you may barely need data — free public Wi-Fi runs on subway trains, buses and in most cafés.
There is a genuine national free wifi network — iTaiwan, over 5,000 hotspots, and since 2020 no registration at all. Connect, open a browser, done.