Mobile coverage in Thailand is genuinely solid — I’ve never run into problems even in the country’s more remote corners. Still, there are a few quirks worth knowing before you land.
AIS vs. True: Thailand’s two networks
Thailand runs on two major networks: AIS and True. I’ve used SIM cards from both, and honestly, the differences in call quality, coverage, and pricing are marginal at best. I started out with True, but once, heading off to another country, I didn’t factor in the need to keep track of my SIM’s expiration date — and True locked the number for good.. Nothing I tried brought it back. I switched to AIS after that, made the exact same mistake with the renewal window, and this time managed to recover the number without issue once I was back in the country. I’ve also come to prefer AIS’s app — it’s simply more intuitive than True’s.
SIMs for a short trip
If you’re only here for a week or two, don’t overthink it — grab whichever network’s counter you reach first at the airport. You’re unlikely to notice any real difference. You can also pick up a tourist SIM at nearly any 7-Eleven.
If your phone supports eSIM, it’s worth considering — short-term rates are roughly the same either way, but you can set everything up from home and skip the counter entirely on arrival.
SIMs for a longer stay
This is where it gets more interesting.
Early in 2026, I learned that the official carrier stores will only sell foreigners tourist SIMs — short validity, no option to renew, and pricier plans. I tested this myself, walking into both AIS and True’s official offices, and got the same answer each time: nothing available to me but the tourist package. My advice, then, is to look for the independent phone stalls instead — the ones selling what I’d call “proper” SIM cards, often at genuinely attractive rates.
Once you’ve got a regular SIM, you can register it in the network’s app, top up easily, track your expiration date, and switch plans whenever you like.
I know SIM cards are also sold on Lazada, Thailand’s answer to Amazon, supposedly with excellent annual rates — but I’ve never bought one there myself, since I can’t rule out complications at activation.
Plans and pricing
I won’t bother listing exact numbers here — carrier pricing shifts constantly, with new promotions appearing all the time, so any figure I give you risks going stale fast.
That said, a few things are worth flagging.
Tourist plans, in my experience, run fairly steep — expect around 400 THB (about $12) for a week of service, with two weeks coming in only slightly cheaper per day. Fine for a short holiday, less fine as a way of life.
The regular plans available through the apps, on the other hand, are a genuinely good deal, and promotions pop up often. I’ve paid that same 400 THB for a full month of 30GB data. At one point, I found a special promotional plan and paid just 120 THB (about $3.50) a month instead.
Annual plans offer the best value of all. They’re not always available in-store — some locations ask for a long-term visa — but they’re open to everyone through the app.
Worth understanding, too, is Thailand’s slightly unusual plan structure. You’re given a base rate when you sign up — mine came with no monthly fee at all — and then you layer packages on top, say, 30GB of data for the month. Once a package runs out — data, minutes, texts — the base rate quietly takes over.
Roaming
If you want your Thai SIM to work abroad, turn on roaming through the app well before you travel. I learned this the hard way once, when it didn’t activate automatically and I spent an unnecessary amount of time sorting it out — the app itself can be glitchy overseas, and it took me more than one attempt to get it working.
Roaming plans, like everything else, can be selected and activated right through the app.
One more thing worth knowing
Every SIM card has an expiration date, visible in the app — and if you’ve linked any services or bank accounts to that number, keep a close eye on it. For security reasons, it seems, once a number goes inactive, the network cuts off the associated account, and Thai bank apps tied to that number lock you out automatically. I found this out firsthand after letting my SIM lapse. Since True refused to restore my old number, I had to buy a new SIM entirely and go into the bank in person to file a request updating my number and unlocking my app access..
To keep an number active, all you need to do is top up — any amount, by card, from any bank. It doesn’t matter whether you’ve bought a data package or not; every top-up simply extends your SIM by another month, regardless of the amount. The maximum validity is one year.
To stretch mine to the full year, I just topped up a small amount every week.
