eSIM & SIM Cards for Southeast Asia & Japan
Data is no longer a luxury on the road — it is the ride home, the map, the translator, and the way you pay. Here is how to land already connected.
Last updated: June 2026.
There was a time when arriving in a new country meant queuing at an airport kiosk, fumbling a tiny plastic chip into a phone, and hoping the agent had set the APN correctly. That era is ending. A traveller can now step off a plane in Bangkok or Tokyo with mobile data already live, bought from a sofa a week earlier and activated the moment the phone finds a signal. This guide explains the three ways to get online in Asia — eSIM, physical SIM, and pocket WiFi — the carriers that matter in each country, and the honest cases where the old plastic chip still beats the new tech. For the wider thread on staying connected without letting the phone run the trip, see Staying Connected and the Mobile section.
Why is mobile data essential when travelling in Asia?
Mobile data has become essential because the modern traveller’s most useful tools all need it: Grab and other ride apps to get a fair fare, Google Maps to navigate, Google Translate’s camera to read a menu or a sign, and QR-code payments that are now standard across the region. Without data you are back to cash, paper maps, and pointing — workable, but slower and dearer.
- Getting around: Grab (Southeast Asia) and similar apps price the trip up front and spare you the metered-taxi theatre. They need a live connection to hail and pay.
- Navigation: Google Maps with live data — transit times, the right exit, the walking route — is hard to do without once you’ve had it.
- Language: Google Translate’s camera mode turns an indecipherable menu into English in real time. See Language Tips.
- Paying: QR payments (PromptPay in Thailand, QRIS in Indonesia, and their cousins) are everywhere, including at market stalls.
eSIM vs physical SIM vs pocket WiFi — which is best?
An eSIM is a digital SIM you buy online and install by QR code, with no plastic to swap — ideal for short trips and arriving pre-connected. A physical SIM is a local chip bought on the ground, usually the cheapest data and giving you a local number. Pocket WiFi is a rented hotspot for groups or heavy users. For most travellers an eSIM is now the default.
| Option | How it works | Best for | Trade-offs |
|---|---|---|---|
| eSIM | Bought online, installed by QR code; keeps your home SIM active alongside it | Short trips, multi-country routes, arriving already connected | Needs an eSIM-capable, unlocked phone; usually data-only (no local number) |
| Physical SIM | Local chip bought at the airport, a telco shop, or a convenience store | Long stays, cheapest data, needing a local phone number | Queue and ID on arrival; you must swap out your home SIM |
| Pocket WiFi | A rented portable hotspot shared by several devices | Families, groups, laptop-heavy travellers, older phones | A second gadget to charge and carry; daily rental adds up; one battery for the group |
Which mobile carrier should I use in each country?
Each Asian country has two or three dominant networks. As a rule, pick the largest incumbent for the widest coverage — AIS or True in Thailand, Viettel in Vietnam, Telkomsel in Indonesia, the big three in Japan. Tourist eSIMs ride on these same networks. The table maps the main telcos and how well eSIM works in each market.
| Country | Main local telcos | eSIM works well? | Notes |
|---|---|---|---|
| Thailand | AIS, True, DTAC | Yes | Cheap, generous tourist data packs; strong coverage on AIS and True. |
| Vietnam | Viettel, Vinaphone, MobiFone | Yes | Viettel has the broadest reach, including the mountains and the coast. |
| Japan | Docomo, au, SoftBank, Rakuten | Yes — tourist eSIMs easiest | Local prepaid SIMs are fiddly for visitors; an eSIM is by far the simplest route. |
| Indonesia | Telkomsel, Indosat, XL | Yes | Telkomsel wins on the outer islands and dive sites; registration needed for physical SIMs. |
| Philippines | Globe, Smart, DITO | Yes | Coverage thins on remote islands; Smart and Globe are the safe pair. |
| Malaysia | Maxis / Hotlink, Celcom-Digi | Yes | Solid 4G/5G on the peninsula; Borneo coverage is patchier off the towns. |
| Cambodia | Cellcard, Smart | Yes | Inexpensive data; Smart and Cellcard both cover the tourist routes well. |
| Taiwan | Chunghwa, Taiwan Mobile, FarEasTone | Yes | Chunghwa is the largest; fast, near-ubiquitous coverage island-wide. |
Which international eSIM app should I use?
Several international eSIM apps sell short-term data plans that work across most of Asia, letting you buy one regional plan instead of a fresh SIM in every country. The best-known are Airalo, Saily, Nomad, Holafly, and Ubigi — each is listed, with the current detail, on our Mobile — eSIM page. Compare price-per-GB, validity, and whether the plan is single-country or regional before buying.
- Airalo, Saily, Nomad, Holafly, Ubigi — all sell country and regional Asia eSIMs you install by QR code. They ride on the local networks in the table above.
- Regional “Asia” plans suit a multi-country trip; single-country plans are usually cheaper per GB if you’re staying put.
- Watch the fine print: some plans are data-only, some throttle after a cap rather than cutting off, and validity windows vary.
- See the full, maintained list and notes on the Mobile page rather than memorising it here — the market moves.
How do I install an eSIM before I fly?
Buy the eSIM in the app a day or two before you fly, while you still have reliable home WiFi, and install it then — but set it to activate on arrival. Installation is a QR-code scan or an in-app tap; your phone stores the profile and your home SIM keeps working until you switch the travel eSIM on. Doing this in advance means you land already connected.
- Check compatibility first: your phone must be eSIM-capable and carrier-unlocked. Most recent iPhones and flagship Android phones qualify; some region-specific models do not.
- Install on home WiFi: scan the QR code or tap “install” in the app before you leave. The profile downloads then; you don’t need it to be active yet.
- Activate on landing: turn on the travel eSIM’s line and enable data roaming for that line. Many plans start their clock at first network connection, so don’t activate days early.
- Keep your home number reachable: leave your home SIM in place for calls and texts (2FA codes), with its data switched off to avoid roaming charges.
When does a local SIM still beat an eSIM?
A local physical SIM still wins for long stays, for a local phone number, and for the cheapest data. If you’re in one country for weeks or months, a local prepaid plan usually undercuts any tourist eSIM on price-per-GB, and a local number lets you receive calls and texts from guesthouses, drivers, and delivery apps that an international data-only eSIM cannot.
- Long stays: a month in Vietnam or Thailand is far cheaper on a local SIM topped up at a convenience store than on rolling eSIM packs.
- A local number: some apps, bookings, and bank verifications expect a local mobile number — a data-only eSIM can’t supply one.
- Cheap, high-volume data: local unlimited and large-cap plans are typically the best value if you’re tethering a laptop or streaming.
- The pragmatic combination: an eSIM to cover the first day or two seamlessly, then a local SIM bought once you’ve found your feet. Best of both.
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