Before you start

Your original passport — photocopies are not accepted for registration
An unlocked handset, or an eSIM-capable one if you want to land connected
For home internet, the property's address and the landlord's cooperation with an installation

Step-by-step

1
Buy and register a SIM at an official store
AIS, True and dtac all have stores at Phuket International Airport and in the island's malls. Staff scan your passport and run a facial-recognition liveness check to confirm you are the holder — about a minute, similar to a banking app selfie. Buying from an official store rather than a general shop means it is registered correctly the first time. There is a cap on how many SIMs one person may hold per operator.
In personWho: You15 to 30 minutesModest for the SIM; tourist data packs cost more but bundle heavily
2
Add a data package immediately
Raw prepaid credit is billed at poor rates and disappears quickly. The value is in the add-on data packages, bought through the operator app, at a 7-Eleven or at a top-up machine. A few hundred baht buys a generous month. Do this the same day you register rather than discovering the credit gone in a week.
Mobile appWho: You5 minutesA few hundred baht for a generous monthly package
3
Ask what fixed-line internet actually reaches the property before you sign
In a Phuket condominium the building is usually served and the provider may be fixed. In a villa, particularly inland or up a hill in Thalang, Kamala or the south, the answer can be that fibre does not reach the lane at all and the existing connection is a fixed-wireless service that degrades in heavy rain. If you work from home, treat this as a lease condition rather than a post-signing problem — and test the actual speed during the viewing, in the room you would work in.
In personWho: YouAsk during the viewingFree to ask
4
Order home internet and allow lead time
AIS Fibre, True and 3BB are the main fixed providers. Installation typically takes several business days to a couple of weeks, longer for a property that has never had a line. Contracts are commonly twelve months with an early-termination charge, which matters if you are on a seasonal lease. Many furnished Phuket rentals already carry a connection in the owner's name — establish whether you take it over or order fresh.
OnlineWho: YouSeveral business days to a couple of weeksModest monthly fee, usually on a twelve-month contract
5
Have a backup if you work from home
Phuket loses power and connectivity in heavy monsoon storms, and villa areas recover more slowly than the main towns. A generous mobile data package on a second network, plus a phone that tethers, is the cheap insurance. People who work to overseas deadlines from the quiet parts of the island all end up with a backup after the first bad week.
Mobile appWho: Remote workersSet up before you need itA second prepaid SIM and package

Documents you’ll need

Original passport (mandatory for SIM registration)
Thai address (for a postpaid plan or a fixed line)
Tenancy agreement and landlord consent for a fixed-line installation

Things most newcomers don’t know

Internet quality on Phuket is a property question, not a provider question.

The developed west coast and the condominium stock around Kathu, Chalong and Phuket Town are generally well served by fibre. Villas inland and up the hills frequently are not, and what looks like a broadband connection can be a fixed-wireless link that degrades badly in the monsoon downpours that arrive most afternoons for half the year. Anyone working to overseas deadlines should test the actual line at the actual property, ideally when it is raining, before committing to a twelve-month lease.

Source: Thai fixed-broadband coverage; Phuket property infrastructure variation

Registration is in person with your real passport and a face scan — there is no remote path for a physical SIM.

Thailand enforces SIM registration through the NBTC and the rules tightened to require original-document checks plus a facial-recognition liveness verification at the counter. Photocopies and remote sign-ups no longer work. The practical consequence is simply to bring your actual passport to the airport counter rather than a photo of it, and to expect a quick selfie-style scan as part of the process.

Source: NBTC SIM registration requirements

A tourist SIM has a hard maximum life and cannot be extended into a long stay.

Tourist data packs are generous and convenient, but they are capped at a fixed number of days and cannot be topped up beyond it — the number simply stops. People who arrive on one, get comfortable, and then find their number dead two months later have usually already linked it to a bank app or a delivery account. If you are staying, switch to a standard prepaid SIM early rather than later.

Source: Thai operator tourist SIM terms

Always add a data package; raw prepaid credit is the expensive default.

Pay-as-you-go data billed against plain credit burns money at rates several times the package price. The cheap, generous deals are the add-on packages bought through the operator app or at any 7-Eleven, and activating one takes two minutes. This is the single most common way newcomers overpay for something Thailand does extremely cheaply.

Source: Thai operator pricing structures

Common mistakes to avoid

Bringing a photocopy rather than the original passport to register a SIM
Running on plain prepaid credit instead of activating a data package
Signing a villa lease on the assumption fibre can be installed, when the lane may not be served at all
Testing internet speed on a clear day and discovering the connection fails in monsoon rain
Staying long-term on a tourist SIM that has a hard expiry and cannot be extended

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.