Getting a Thai number is one of the first things you should do on arrival — it unlocks delivery apps, banking, ride-hailing and two-factor logins. Here’s how the three networks compare, the difference between tourist SIMs, prepaid and postpaid, how eSIM works, what data really costs, where to buy, and the passport rule you can’t skip.
A local SIM is the spine of daily life in Thailand. Almost everything — food delivery, grab rides, mobile banking, PromptPay, building chat groups and OTP logins — assumes a working Thai mobile number. The good news: SIMs are cheap, fast to set up, and you can be online within minutes of landing.
AIS is the largest operator and generally has the widest, most reliable coverage nationwide — the safe pick if you will live or travel outside the big cities or on islands. TrueMove H is strong across Bangkok and the major tourist centres and frequently runs the punchiest promotions and bundles. dtac, which now operates alongside True following their merger, competes hard on price. In everyday city use the three feel similar, so most newcomers simply chase the best current data deal; if coverage in remote areas matters, lean AIS.
A tourist SIM is the no-friction option for short stays: pay once for a fixed block of data (often unlimited) valid for 8, 15 or 30 days, with nothing to cancel. For longer stays, a monthly prepaid top-up or a postpaid (contract) plan works out cheaper per gigabyte. Postpaid usually wants a Thai address — and sometimes a work permit, longer-stay visa or deposit — so a great many foreigners just keep a prepaid SIM and renew a recurring monthly data package, which behaves like a plan without the paperwork.
All three networks support eSIM on compatible phones, and you can buy a travel eSIM online before departure so you land with data already live. eSIM lets you keep your home SIM or number active on a second line — handy for verification codes from your home bank. For longer stays a locally bought physical SIM is usually cheaper and trivially easy to top up at any convenience store. Either way, the passport-registration rule below still applies to locally issued eSIMs.
Mobile data in Thailand is inexpensive. Tourist SIMs commonly land around 300–600 baht for one to four weeks of generous or unlimited data. Monthly prepaid packages might be a few hundred baht for tens of gigabytes plus some call minutes, while heavy-use unlimited plans cost more. Bonus data, promo bundles and pricing shift constantly and differ by network and shop, so always compare the current packages in the network app or in-store before you buy — and factor this small, predictable cost into your cost-of-living planning.
You have three easy options. Airport counters (AIS, True and dtac all have desks in the arrivals halls at Suvarnabhumi, Don Mueang, Phuket and Chiang Mai) are the fastest way to get online the moment you land, though tourist bundles there carry a small convenience premium. Official network shops in malls give you the full range of plans, English-speaking staff and help with eSIM or number porting. And 7-Eleven — one is never far away — sells starter SIMs and handles registration and top-ups. See our guide to 7-Eleven & daily life for how central these stores are.
Thai law requires every SIM to be registered to an identity document, so bring your passport when you buy. The shop scans it and registers the SIM to you in a couple of minutes — airport counters, network shops and 7-Eleven all do this for you. Steer clear of pre-loaded SIMs sold informally without registration: an unregistered or mis-registered number can be suspended without notice, cutting off the OTP codes your banking and apps rely on.
Adding credit and activating data are two separate steps. Top up your balance at any 7-Eleven (just give your number), at network shops, via the AIS/True/dtac apps, at ATMs, or through your Thai banking app and PromptPay once you have an account. Then select a data package in the app or by dialling a short USSD code. Watch the validity dates so your number stays active — a Thai number is often tied to your bank and app logins, so letting it lapse is a hassle worth avoiding. Opening a local account makes auto-renewals seamless; see opening a Thai bank account.
Thailand supports mobile number portability, so you can move your Thai number between AIS, True and dtac if another network has better coverage or a better deal — you keep the same digits. It is a quick in-store process with your passport. For most newcomers this only matters later, once you have settled and noticed where your network is weak; for digital nomads who depend on a stable connection, our remote-work guide covers connectivity, coworking and backup data in more depth.
General information only; network coverage, plan availability, data-package prices, registration rules and payment options vary by location and change over time — confirm with the network or shop before buying. AIS, TrueMove H and dtac are trademarks of their respective owners; BAANLYY is not affiliated with or endorsed by any of them.