eSIM for Thailand

Half a Thailand trip gets arranged on the move: a Grab to the pier, a LINE message to a guesthouse that gets answered in ten seconds, a ferry departure that quietly moved since the website last said otherwise. A Thai eSIM covers all of that from the arrivals hall onward, whether you come in at Suvarnabhumi, Don Mueang, Phuket, Chiang Mai or Samui. Your usual number stays live in the background for bank codes and messages from home.

Getting online when you land

Set the profile up before you leave, over wifi at home. Installing needs a connection, and the airport is the worst possible place to find that out. Keep the line dormant until you arrive.

Off the plane, switch the travel line on, make it your data line, and enable data roaming for it if your phone asks. Turn mobile data off on your home line so nothing sneaks through it. You should be connected by the time you reach passport control, which matters, because the ride-hailing pickup points at Suvarnabhumi and Don Mueang are signposted for people who already have a booking open on screen.

If you are connecting straight onto a domestic flight or an overnight bus, load the boarding pass or ticket while you are still standing still. Terminal signal beats signal on a bus grinding out of the city.

The networks you'll be on

In Thailand you connect through AIS or DTAC. Both run 4G/LTE and 5G, the phone attaches on its own, and there is no setting for you to get wrong.

Day to day that means dependable 4G/LTE nearly everywhere people live and stay, with 5G in Bangkok and the larger tourist centres. It is comfortably enough for video calls from a beach bar, which is really the benchmark most people care about.

Where coverage holds, and where it thins

Bangkok is dense and thoroughly covered: on the street, on the BTS and MRT, inside the malls, up in the towers. Chiang Mai, Phuket, Pattaya and Krabi behave the same way around town, along the main beach strips and on the highways linking them.

The gaps are roughly where you would guess. Ferry crossings to Koh Samui, Koh Tao and the Phi Phi islands lose signal in the middle, and the far ends of the smaller islands, away from the main village and the pier, can be thin. Inland, the hill roads on the Mae Hong Son loop and around Pai, national parks like Khao Sok and Khao Yai, and rural stretches of Isan between towns will hand you one bar or nothing. Limestone karst plays tricks too: full signal in the boat, none in the lagoon behind the rock.

What you'll actually use data for here

Ride-hailing comes first. Grab and Bolt in the cities take the fare haggling out of the day entirely, and being able to drop a pin outside a temple whose name you cannot pronounce is worth the connection on its own.

Messaging is close behind, and specifically LINE. It is how a lot of Thai businesses actually talk to customers: guesthouses, dive shops, drivers and tour operators will show you a QR code to add them, then reply within minutes. Plenty of bookings here exist only as a LINE thread. WhatsApp works fine, but LINE is the local default.

After that it stacks up quickly. Reading Thai script through a camera, checking ferry and sleeper train times that shift with the season and the weather, working out which pier a boat actually leaves from as opposed to which pier the ticket says, doing constant mental arithmetic with a converter app, and uploading photos while the beach still looks like that.

Before you fly

Download offline maps of the islands and any hill routes you plan to drive or ride. The dead spots are short, but they show up at exactly the turn where you needed a map.

Screenshot whatever you cannot lose: ferry and bus tickets, your accommodation with its Thai name and a phone number, and the address written in Thai script to hand to a driver. Small island guesthouses are frequently not where the map pin claims they are, and a number solves that in one call.

Bring a power bank and something waterproof to keep the phone in. Longtail boats, wet-season downpours and full-day snorkelling trips are hard on phones, and a flat battery is the one thing an eSIM cannot fix for you. Finally, turn your home line's data roaming off before takeoff so the travel line handles everything.