Mobile Internet in Thailand: Tourist SIM vs eSIM vs Roaming, and How Much Data You Need

In Phuket your phone is your taxi, your map, your translator and often your wallet. Grab needs data, Google Maps needs data, and the restaurant you are looking for is easier to find with a live map than with a screenshot. The good news: mobile coverage on the island is strong, 4G is everywhere tourists go and 5G covers much of the populated area. The only question is how you buy access. There are three ways, and each suits a different traveller.

The three options in one table

Option 1: Thai tourist SIM at the airport

In the arrivals hall at Phuket Airport, the big Thai operators — AIS and True (which merged with dtac in 2023, though both brands are still sold) — run counters that sell tourist SIM packages. The packages are time-limited: commonly around 8, 15 or 30 days, with a fixed or very large data allowance and sometimes a little call credit. Prices are posted at the counter; tourist packs have historically been in the low hundreds of baht for about a week and higher for a month. Check current packages at the counter, because the line-up changes several times a year.

What to know:

• Bring your passport. Thai law requires SIM cards to be registered to an identity document. The staff scan your passport and may take a photo of you. Without registration the SIM will not work.
• Your phone must be unlocked. A phone locked to your home carrier will not accept a foreign SIM. Check before you fly.
• Queues happen. When several wide-body flights land together, the queue at the SIM counters can take a while. If you want to leave the airport quickly, the eSIM option avoids this.
• You get a Thai number. This helps with local deliveries, restaurant bookings, some apps and anything that wants an SMS code to a Thai number. Hotels, tour operators and rental companies also find it easier to call a Thai number.
• Keep the SIM card holder. It shows your number and package details, which you will need if you top up.

Carrier shops in shopping malls and 7-Eleven stores across the island also sell SIMs and top-ups, but the dedicated tourist packages are most convenient at the airport counters and official carrier shops.

Option 2: Travel eSIM

An eSIM is a digital SIM profile you download to your phone, usually by scanning a QR code or through an app. You can buy and install it at home, and it activates when you land. There are two kinds:

• Data-only eSIMs from international resellers. Sold by data volume (for example several gigabytes for a week or two) or as "unlimited" plans with a fair-use limit. They connect through a Thai network, but you usually get no Thai phone number.
• Tourist eSIMs from Thai carriers. AIS and True sell tourist packages as eSIMs online. These behave like the airport SIM — including a Thai number — but still require identity registration, usually by uploading a passport photo or completing it on arrival. Follow the carrier's instructions exactly.

Before you buy, check three things:

1. Your phone supports eSIM. Most recent iPhones and many Android flagships do; many budget phones do not. On most phones, dialling *#06# shows an "EID" number if eSIM is supported. Also check in Settings under mobile/cellular.
2. Your phone is unlocked, the same as for a physical SIM.
3. Read what "unlimited" means. Many plans slow you down sharply after a daily or total high-speed allowance. That is fine for maps and messaging but frustrating for video calls.

Install the eSIM at home over Wi-Fi, but follow the provider's activation rules: some plans start counting days at installation, others at first connection in Thailand. Leave the eSIM line switched off for data until you land, and turn on "data roaming" for that line — many travel eSIMs technically roam on the Thai network, and the phone will not connect without it.

Option 3: Roaming with your home operator

Roaming is the easiest option: nothing to install, your number works as usual. Whether it is sensible depends entirely on your home tariff. Some plans include Thailand or offer a daily travel pass at a fixed price; on many others, pay-as-you-go roaming outside your home region is extremely expensive per megabyte. Check your operator's price for Thailand before you fly, and if it is not included, switch off data roaming for your home line as soon as the plane lands — background app updates can run up a large bill within hours.

A sensible combination for many travellers: keep the home SIM active for calls and SMS (bank codes, for example) with data roaming switched off, and use a Thai SIM or eSIM for data. Dual-SIM and eSIM phones make this easy.

How much data do you actually need?

Usage varies a lot, but these rough figures help you size a plan:

• Google Maps navigation: modest — typically a few megabytes to a few tens of megabytes per hour of driving. Downloading the Phuket offline map at the hotel reduces it further.
• Grab and Bolt rides: very little per ride.
• Messaging (WhatsApp, Telegram, LINE), text and photos: low, unless you send many videos.
• Voice calls over apps: roughly half a megabyte to one megabyte per minute.
• Video calls: heavy — several megabytes per minute, more in HD.
• Instagram, TikTok, YouTube: the real data eaters. Short-video scrolling can easily use 1 GB or more per hour.
• Uploading your own videos and photo backups: large; set cloud backup to Wi-Fi only.

In practice:

• Light user (maps, Grab, messengers, some browsing, hotel Wi-Fi for the rest): around 0.5–1 GB per day.
• Typical tourist (plus social media and some video calls): around 1–3 GB per day.
• Heavy user or remote worker (streaming, hotspot for a laptop, frequent video calls): 3–10 GB per day or an unlimited plan without a strict speed cap.

For two weeks, a typical tourist is comfortable with around 15–30 GB. If you plan to share a hotspot with a partner or children, multiply accordingly. Hotel Wi-Fi in Phuket is generally decent but varies a lot between properties and rooms.

Which option should you choose?

• Short trip, phone supports eSIM: a travel eSIM installed before departure. You land connected and order a car from the plane door.
• Longer stay, or you need a Thai number (for local deliveries, renting a condo, a Thai bank, calls with your rental company): a Thai carrier SIM or the carrier's own tourist eSIM.
• Your home plan includes Thailand: roaming, with no extra effort.
• Older or locked phone: roaming or a pocket Wi-Fi router, or get the phone unlocked by your operator before the trip.

Practical tips for Phuket

• Download the offline Google Map of Phuket before you set off on day trips; signal can be weaker on remote viewpoints, some beaches and on boats to the islands.
• On boat trips to Phi Phi, Similan or James Bond Island expect gaps in coverage at sea.
• If you ride a scooter or drive, mount the phone securely; holding a phone while driving is an offence.
• Save your hotel address and your rental company's number in the phone in case the battery runs low and you need to show it to a driver.
• Carry a small power bank: navigation and a hot climate drain batteries quickly.
• Be careful with public Wi-Fi for banking; mobile data is generally safer than open hotspots.

Common questions at the counter

Can I keep my WhatsApp number? Yes. WhatsApp stays tied to your home number even when you use data from a Thai SIM or eSIM. Do not re-register WhatsApp with the Thai number unless you want to.

Can I top up later? Yes, at carrier shops, 7-Eleven or through the carrier's app; for travel eSIMs, in the reseller's app.

Is 5G worth paying extra for? For most tourists no; 4G is fast enough for maps, calls and social media. It matters only if you work online with large uploads.