Using an eSIM in Bangkok

What Bangkok is like on a phone

Bangkok is both a destination and the region's transfer hall: some people stay two nights before flying down to an island, others settle in for a month and work from cafes. The network here is unusually dense for a Southeast Asian capital, with almost no dead spots along the elevated rail corridors, inside malls, or on underground platforms. What actually frustrates people is not absence of signal but the sheer number of handsets on the same cell at rush hour, when everything slows at once. Plan around congestion, not around coverage.

When you land

Two gateways handle arrivals: Suvarnabhumi (BKK) and Don Mueang (DMK). Switch the eSIM line on as the wheels touch down — you normally have service before you reach immigration. At Suvarnabhumi the Airport Rail Link runs from the basement to Phaya Thai and connects onward to the city rail; from Don Mueang most people take a car or the commuter train. If you order a car in an app, the pick-up point is usually on a different floor from the arrivals doors, so read the door number in the app before you start walking. On the expressway into town your map will recalculate several times as the traffic ahead rearranges itself.

Where coverage changes

The elevated and underground rail lines are the spine of coverage here: platforms below ground and the tunnel sections between them stay usable. Turn off a main road into a deep soi walled by tall shophouses on both sides, though, and speed drops noticeably in places. On the Chao Phraya express boats you keep service almost the whole way because both banks are built up, but the wider mid-river stretches can stutter briefly as the phone hands from one mast to the next. In a market packed shoulder to shoulder — Chatuchak on a weekend is the obvious case — the problem is the queue of people using the same cell, not the lack of one.

What a day here costs in data

A normal sightseeing day here runs through roughly 1–2GB, because the map stays open and you order cars several times over. Scanning a QR code to pay at a food stall costs almost nothing in data but needs you online every single time, which is why shop Wi-Fi is a bad thing to lean on while you are standing in a queue. Camera translation pointed at signboards and menus eats more than people expect. On an evening when you upload a long clip or go live from a rooftop, budget roughly double an ordinary day.

Districts travellers ask about

• Sukhumvit — The city's longest rail corridor, steady on platforms and inside malls, though a few of the deeper even-numbered sois need you to step somewhere open before a map will load.
• Silom–Sathorn — An office district that fills and empties on a schedule; at lunch and again at knock-off time the whole neighbourhood slows together, so avoid booking a call into those two windows.
• Rattanakosin old town — Low buildings and open ground around the palace and old temples mean signal arrives cleanly, but inside a few of the thick masonry halls it weakens enough that photos stop uploading.
• Ari–Chatuchak — Ari is cafe territory where people work all day, while Chatuchak on Saturday and Sunday gets crowded enough that a message can sit for a moment before it goes.

Day trips out of the city

• Ayutthaya — An hour and a half north by train or van with service the whole way, though out among the open fields and brick ruins the line feels thinner than it does downtown.
• Amphawa floating market — A Friday-to-Sunday evening trip; along the canal bank you stay connected, but once the firefly boat turns into the narrower waterways under overhanging trees, service can come and go.
• Kanchanaburi — About three hours west; the town and the riverfront behave normally, but once the road climbs toward the waterfalls and park land the line starts dropping out, so save the map area before you leave town.