Mobile coverage is broad in cities and tourist destinations, but may fall away on small islands, in parks and along remote roads. Compare current operator and provider plans rather than looking only at the advertised data allowance.
Main options
| Option | Advantages | Limitations |
|---|---|---|
| Travel eSIM | Installs before departure and keeps the physical SIM in place | Often data-only; tethering and network depend on the plan |
| Local tourist SIM | May include a Thai number and in-store support | Requires an unlocked phone and a SIM swap |
| International roaming | Keeps the usual number and setup | May have high costs or low limits |
| WiFi | Useful in hotels and cafes | Variable quality and no coverage while travelling |
AIS, True and dtac are familiar brands, but plans, coverage and commercial ownership can change. Review coverage maps and terms through official channels, especially for islands and rural areas.
Before buying
Confirm that the phone is unlocked, supports the required bands and is eSIM-compatible if relevant. Check when validity starts, whether speed is reduced after a threshold, whether tethering is allowed and whether calls are included.
A local SIM may require passport registration. Buy from an official outlet or recognised distributor and retain the packaging with the number and instructions.
Setup and arrival
- Save the QR code or instructions somewhere other than email.
- Install the eSIM on WiFi if instructed, without starting its validity early.
- Disable data roaming on your usual line if it is not included.
- On arrival, select the new line for data and follow the operator's APN instructions.
- Test maps, messaging and the transport app before leaving.
Data allowance
Maps, messages and bookings use relatively little data when content is downloaded in advance. Video, photo backups, video calls and tethering use much more. Review your own phone's weekly usage and add a margin rather than relying on a generic daily figure.
Download before flying:
- maps for Bangkok and other destinations;
- Thai in the translation app;
- bookings, insurance documents and tickets;
- entertainment for long journeys.
WiFi and security
Hotels, shopping centres and cafes often provide WiFi, with variable quality. Ask the accommodation directly if you need to work or make video calls. Avoid sensitive transactions on open networks or use your organisation's required protections.
Storms, power cuts and congestion can affect service. Keep essential addresses and documents offline.
Checklist
- ☐ Phone unlocked and compatible
- ☐ Coverage reviewed for the entire route
- ☐ Validity, limits and tethering confirmed officially
- ☐ QR code, number and support details saved offline
- ☐ Roaming on the usual line configured
- ☐ Emergency numbers saved: 191 for police and 1669 for medical emergencies