To call a Thai number from abroad, dial +66 and leave out the first 0: the Bangkok number 02-624-5200 becomes +66 2 624 5200. Keeping a Thai SIM alive while you are away is harder than writing the number correctly, and it matters if your Thai bank sends its one-time codes to it.
Inside Thailand, every ordinary number starts with 0. That 0 is a domestic trunk prefix, not part of the number itself, so it disappears the moment you add the country code. Thai official pages use both styles: the MRT operator lists its office as 02-624-5200, while Airports of Thailand prints its taxi counter as +66 2 132 0360.
This page is about the number itself: how to write it, how to dial it, and how to stop losing it. Choosing and buying a SIM or eSIM is covered in our guide to SIM cards versus eSIMs in Thailand.
Thai numbers at a glance (October 2026)
- Country code
- +66 (drop the leading 0)
- Bangkok landline
- 02-xxx-xxxx at home, +66 2 xxx xxxx from abroad
- Mobile
- Ten digits at home, starting 0 (for example 084, 094); nine digits after +66
- Four-digit hotlines
- National short codes such as 1155 or 1166; plan for them not to work from abroad
- SIM registration
- Passport, in person; at most 3 SIMs per foreigner per operator (NBTC, since 16 May 2026)
- Tourist SIM validity
- Never more than 60 days; cannot be revived by a top-up after expiry (True)
Reading a Thai number: the zero, the area code and the brackets
A Bangkok landline has a one-digit area code, 2, so it is written 02 plus seven digits. Provincial landlines have two-digit codes: the Tourism Authority's Udon Thani office is +66 42 325 407, and its Nakhon Si Thammarat office is printed as +66 (0) 7534 6515. That "(0)" means "dial this zero only when you are in Thailand". From abroad, skip it.
Mobile numbers have ten digits in Thailand, written 08x-xxx-xxxx or 09x-xxx-xxxx in most listings you will see, for example the airport shuttle counter at +66 84 718 8800. We could not read the regulator's own numbering plan, so do not take those first digits as a complete list; any Thai number that starts with 0 and has ten digits is almost certainly a mobile.
| Written in Thailand | Type | Dial from abroad |
|---|---|---|
| 02-624-5200 | Bangkok landline | +66 2 624 5200 |
| 042-325-407 | Provincial landline (Udon Thani) | +66 42 325 407 |
| 084-718-8800 | Mobile | +66 84 718 8800 |
| 1155 | National hotline (Tourist Police) | No international form |
When you save a Thai number in your phone, save it in the +66 form. It then works from Thailand and from abroad, and messaging apps such as WhatsApp recognize it.
Calling out of Thailand
On a mobile, the + sign does the work: hold the 0 key until + appears, then the country code and the number. Operators also sell cheaper international access codes; AIS, for example, names 00300 on its tourist SIM page. The rates differ by code and plan, so check them in the operator's app before a long call.
For most people the cheaper answer is not to dial at all. A call over LINE or WhatsApp uses data, works on hotel Wi-Fi and costs nothing extra. LINE is very widely used in Thailand, and many landlords, clinics and small hotels prefer it to a phone call. Our guide to internet and mobile data in Thailand covers the connection itself.
Short four-digit numbers: why they fail from abroad
Thailand runs many services on four-digit hotlines: 1155 for the Tourist Police, 1166 for the consumer protection board, 1175 for AIS, 1242 for True and 1678 for dtac. These are national short codes. There is no "+66 1155", so do not expect them to connect from a foreign number or from outside the country; we found no official statement that they do. Look for the organization's full number (often an 02 landline) or its LINE account instead, and save that before you leave.
The short emergency numbers work differently and have their own page: our list of emergency numbers in Thailand explains 191, 1669, 199 and 1155. For complaints about shops and services, see who to contact when something goes wrong.
A Thai number is registered to your passport
Every Thai SIM has to be registered to a person. For foreigners that is done with a passport. An NBTC notification published in the Royal Gazette on 15 May 2026, in force from 16 May 2026, limits people without Thai nationality to three SIMs per person per operator and says registration must be done in person at a branch or authorized dealer, according to the law firm Tilleke & Gibbins. True's tourist SIM page repeats the same three-SIM limit.
The same rules say a registered SIM must be activated within 60 days. If it is not, the owner has to verify their identity again in person. AIS adds that a tourist who wants to keep a tourist SIM beyond 60 days from activation must reconfirm their identity, either by sending the passport number by SMS to 4444161 and following the link in the reply, or at an AIS shop.
Never use a SIM registered to someone else. A number in a friend's, landlord's or agent's name is not yours: you cannot verify it, move it or recover it, and the bank that sends codes to it is dealing with the wrong person. Register your own number with your own passport.
Keeping a prepaid number alive while you are abroad
Tourist SIMs are built to expire. True states that tourist SIM validity may not exceed 60 days and cannot be extended by a top-up after expiry; to keep using the service you must identify yourself again with a passport at a shop. True also says its tourist packages do not include prepaid international roaming. In practice, a tourist SIM is a poor home for anything you will need after the holiday.
If you live in Thailand or come back often, ask for an ordinary prepaid or monthly plan in your own name instead. Before you leave the country, ask the shop three questions and write down the answers:
- How long does the number stay active after the last top-up, and what happens when that runs out?
- Can the plan receive SMS while roaming abroad, and what does that cost?
- Can you top up from abroad in the operator's app with a foreign card?
Top-ups inside Thailand are easy: True lists its shops and 7-Eleven, with amounts from 20 baht, and AIS runs top-ups through its myAIS app. Whether a foreign card is accepted for an app top-up varies, and we could not confirm it for any operator, so test it while you are still in Thailand. A monthly plan billed to a Thai bank account avoids the problem, as long as the account stays open.
Bank codes, roaming and the second SIM slot
The number matters most for one-time passwords. Many Thai banking apps, and some official services, send codes by SMS to the number registered with them. Our guide to opening a bank account in Thailand explains why the bank wants a Thai number in your name; if that number dies while you are abroad, you may be locked out until you visit a branch.
The simplest protection is a phone with two SIM slots, or one physical SIM plus an eSIM. Keep the Thai SIM switched on for SMS with data roaming off, and use your home SIM or a local one for data. Ask what your Thai plan charges for receiving an SMS abroad. If the bank offers app-based approval instead of SMS codes, set that up before you travel.
Change the bank's number before you change the SIM. If you plan to swap your Thai number, register the new one with your bank first, at a branch if needed. Doing it the other way round can leave you without the codes you need to make the change.
Text messages that ask you to click a link "to keep your number active" or "to verify your bank" are a classic scam; Thai banks may not send links by SMS. Our page on phone scams and SMS phishing in Thailand covers them, along with the 1441 anti-scam hotline. If your embassy offers registration abroad, give it a number that will work: see registering with your embassy.
If the number dies anyway
When a Thai prepaid number has expired, the operator may let you reclaim it in person with the same passport, or it may already have been released. Ask at a branch of the same operator first. Then, in this order, update the number with your bank, your landlord or condo office, and any app or service that logs you in by SMS. Keep LINE or WhatsApp linked to an email address as well as a phone number, so you can still be reached while you sort it out.
Long-stay readers will find more on settling in at our living and working in Thailand hub, and our guide to wintering in Thailand covers the rhythm of coming and going each year.
Frequently asked questions
How do I write a Thai number in international format?
Put +66 in front and remove the leading 0. A Bangkok landline 02-123-4567 becomes +66 2 123 4567, and a mobile 081-234-5678 becomes +66 81 234 5678. Spaces do not matter to the phone, only the digits.
Can I call a Thai four-digit hotline from abroad?
Plan on no. Numbers such as 1155, 1166 or an operator's call center are national short codes with no +66 version. Look up the organization's full landline number or its LINE account, and save it before you leave Thailand.
How long does a Thai tourist SIM stay active?
True says no tourist SIM may be valid for more than 60 days and that a top-up cannot extend it after expiry. AIS says tourists who want to keep a tourist SIM beyond 60 days from activation must reconfirm their identity. For a longer stay, ask for an ordinary plan in your own name.
How many Thai SIM cards can a foreigner have?
Three per person per operator, under an NBTC notification in force since 16 May 2026, as described by Tilleke & Gibbins and repeated on True's tourist SIM page. Registration uses your passport and is done in person at a shop or authorized dealer.
Sources
- Tilleke & Gibbins – Thailand tightens telecom registration, data and IP address rules to combat tech crime (2026) (checked October 2026)
- True – Thailand Tourist SIM: terms, validity rules and top-up (checked October 2026)
- AIS – Tourist SIM and identity reconfirmation (checked October 2026)
- BEM (MRT operator) – Facilities and contact numbers (checked October 2026)
- Airports of Thailand – Suvarnabhumi Airport (checked October 2026)
- UK Foreign Office – Thailand: getting help (checked October 2026)