Since the beginning of 2002 Thailand no longer uses domestic area codes. These have all now been incorporated into the telephone number so even when calling within the local area, the area code must be dialled. Some confusion exists regarding the first (0) digit; if you try dialling without it and you can't get through then dial again with it.
You will still find many telephone numbers in the old format, Bangkok & environs: 7 digits, provinces: 6 digits. To help you convert to the new country-wide number format of 8 digits here are the old area codes for some of the major cities around Thailand. Remember to also add the optional zero if at first you don't succeed.
| For | Dial | For | Dial |
| Amnatcharoen | 45 | Ang Thong | 35 |
| Ayutthaya | 35 | Bangkok | 2 |
| Buriram | 44 | Chachoengsao | 38 |
| Chai Nat | 56 | Chaiyaphum | 44 |
| Chanthaburi | 39 | Chiang Mai | 53 |
| Chiang Rai | 53 | Chonburi | 38 |
| Chumphon | 77 | Kalasin | 43 |
| Kanchanaburi | 34 | Kamphaeng Phet | 55 |
| Khon Kaen | 43 | Krabi | 75 |
| Lampang | 54 | Lamphun | 53 |
| Loei | 42 | Lopburi | 36 |
| Mae Hong Son | 53 | Maha Sarakham | 43 |
| Mukdahan | 42 | Nakhon Nayok | 37 |
| Nakhon Pathom | 34 | Nakhon Ratchasima | 44 |
| Nakhon Sawan | 56 | Nakhon Si Thammarat | 75 |
| Nan | 54 | Narathiwat | 73 |
| Nong Bua Lumphu | 42 | Nong Khai | 42 |
| Nonthaburi | 2 | Pathumthani | 2 |
| Pattani | 73 | Phang-Nga | 76 |
| Phayo | 54 | Phetchabun | 56 |
| Phetchaburi | 32 | Phatthalung | 74 |
| Phichit | 56 | Phitsanulok | 55 |
| Phrae | 54 | Phuket | 76 |
| Prachinburi | 37 | Prachuap Khiri Khan | 32 |
| Ranong | 77 | Ratchaburi | 32 |
| Rayong | 38 | Roi Et | 43 |
| Sa Kaew | 37 | Sakon Nakhon | 42 |
| Samut Prakan | 2 | Samut Sakhon | 34 |
| Samut Songkhram | 34 | Saraburi | 36 |
| Satun | 74 | Sing Buri | 36 |
| Si Sa Ket | 45 | Songkhla | 74 |
| Sukhothai | 55 | Suphanburi | 35 |
| Surat Thani | 77 | Surin | 44 |
| Tak | 55 | Trat | 39 |
| Trang | 75 | Ubon Ratchathani | 45 |
| Udon Thani | 42 | Uthai Thani | 56 |
| Uttaradit | 55 | Yala | 73 |
| Yasothon | 45 |
International Access code is: 001
| For | Dial | For | Dial |
| Afghanistan | 93 | Albania | 355 |
| Algeria | 213-215 | American Samoa | 684 |
| Andorra | 376 | Angola | 244 |
| Anguilla | 1 | Antigua | 1 |
| Argentina | 54 | Armenia | 374 |
| Aruba | 297 | Ascension | 247 |
| Australia | 61 | Australian External | 672 |
| Austria | 43 | Azerbaijan | 994 |
| Bahamas | 1 | Bahrain | 973 |
| Bangladesh | 880 | Barbados | 1 |
| Belarus | 375 | Belgium | 32 |
| Belize | 501 | Benin | 229 |
| Bermuda | 1 | Bhutan | 975 |
| Bolivia | 591 | Bosnia-Herzegovina | 387 |
| Botswana | 267 | Brazil | 55 |
| British Virgin Islands | 1284 | Brunei | 673 |
| Bulgaria | 359 | Burkina Faso | 226 |
| Burundi | 257 | Cambodia | 855 |
| Cameroon | 237 | Canada | 1 |
| Cape Verde | 238 | Cayman Islands | 1 |
| Central African Republic | 236 | Chad | 235 |
| Chile | 56 | China | 86 |
| Columbia | 57 | Comoros | 269 |
| Congo | 242 | Cook Islands | 682 |
| Costa Rica | 506 | Croatia | 385 |
| Cuba | 53 | Cyprus | 357 |
| Czech Republic | 420 | Denmark | 45 |
| Diego Garcia | 246 | Djibouti | 253 |
| Dominica | 1 | Dominican Republic | 1 |
| East Timor | 670 | Egypt | 20 |
| Ecuador | 593 | El Salvador | 503 |
| Equatorial Guinea | 240 | Eritrea | 291 |
| Estonia | 372 | Ethiopia | 251 |
| Falkland Islands | 500 | Faroe Islands | 298 |
| Fiji | 679 | Finland | 358 |
| France | 33 | French Guiana | 594 |
| French Polynesia | 689 | Gabon | 241 |
| Gambia | 220 | Georgia | 995 |
| Germany | 49 | Ghana | 233 |
| Gibraltar | 350 | Greece | 30 |
| Greenland | 299 | Grenada | 1 |
| Guadeloupe | 590 | Guam | 671 |
| Guatemala | 502 | Guinea | 224 |
| Guinea Bissau | 245 | Guyana | 592 |
| Haiti | 509 | Honduras | 504 |
| Hong Kong | 852 | Hungary | 36 |
| Iceland | 354 | India | 91 |
| Indonesia | 62 | Iran | 98 |
| Iraq | 964 | Ireland | 353 |
| Israel | 972 | Italy | 39 |
| Ivory Coast | 225 | Jamaica | 1 |
| Japan | 81 | Jordan | 962 |
| Kazakhstan | 7 | Kenya | 254 |
| Kyrgyzstan | 996 | Kenya | 254 |
| Kiribati | 686 | Korea - North | 850 |
| Korea - South | 82 | Kuwait | 965 |
| Laos | 856 | Latvia | 371 |
| Lebanon | 961 | Lesotho | 266 |
| Liberia | 231 | Libya | 218-219 |
| Liechtenstein | 423 | Lithuania | 370 |
| Luxembourg | 352 | Macau | 853 |
| Macedonia | 389 | Madagascar | 261 |
| Malawi | 265 | Malaysia | 60 |
| Maldives | 960 | Mali | 223 |
| Malta | 356 | Marshall Islands | 692 |
| Martinique | 596 | Mauritania | 222 |
| Mauritius | 230 | Mayotte | 269 |
| Mexico | 52 | Micronesia | 691 |
| Midway & Wake Islands | 1 | Moldova | 373 |
| Monaco | 377 | Mongolia | 976 |
| Montserrat | 1 | Morocco | 210-212 |
| Mozambique | 258 | Myanmar | 95 |
| Namibia | 264 | Nauru | 674 |
| Nepal | 977 | Netherlands | 31 |
| Netherlands Antilles | 599 | New Caledonia | 687 |
| New Zealand | 64 | Nicaragua | 505 |
| Niger Republic | 227 | Nigeria | 234 |
| Niue | 683 | Norway | 47 |
| Oman | 968 | Pakistan | 92 |
| Palau | 680 | Palestine | 970 |
| Panama | 507 | Paraguay | 595 |
| Papua New Guinea | 675 | Peru | 51 |
| Philippines | 63 | Poland | 48 |
| Portugal | 351 | Puerto Rico | 1 |
| Qatar | 974 | Reunion | 262 |
| Romania | 40 | Russia | 7 |
| Rwanda | 250 | Saipan Islands | 670 |
| San Marino | 378 | Sao Tome & Principe | 239 |
| Saudi Arabia | 966 | Senegal | 221 |
| Seychelles | 248 | Sierra Leone | 232 |
| Singapore | 65 | Slovak Republic | 421 |
| Slovenia | 386 | Solomon Islands | 677 |
| Somalia | 252 | South Africa | 27 |
| Spain | 34 | Sri Lanka | 94 |
| St. Christopher & Nevis | 1 | St. Helena | 290 |
| St. Lucia | 1 | St. Pierre & Miquelon | 508 |
| St. Vincent | 1 | Sudan | 249 |
| Suriname | 597 | Swaziland | 268 |
| Sweden | 46 | Switzerland | 41 |
| Syria | 963 | Tahiti | 689 |
| Taiwan | 886 | Tajikistan | 992 |
| Tanzania | 255 | Thailand | 66 |
| Togo | 228 | Tokelau | 690 |
| Trinidad & Tobago | 1 | Tunisia | 216-217 |
| Turkey | 90 | Turkmenistan | 993 |
| Turks & Caicos | 1 | Tuvalu | 688 |
| Ukraine | 380 | Uganda | 256 |
| United Arab Emirates | 971 | United Kingdom | 44 |
| Uruguay | 598 | USA | 1 |
| US Virgin Islands | 1 | Uzbekistan | 998 |
| Vanuatu | 678 | Venezuela | 58 |
| Vietnam | 84 | Wallis & Futuna Islands | 681 |
| Western Samoa | 685 | Yemen | 967 |
| Yugoslavia | 381 | Zaire | 243 |
| Zambia | 260 | Zimbabwe | 263 |
Thailand Direct Service allows Thais abroad to contact an operator in Thailand directly to make a call. Calls are charged at Thailand overseas operator rates.
| From | Dial | From | Dial |
| Australia (Telstra) | 1-800-881-660 | Australia (Opus) | 1-800-55-11-66 |
| Brunei | 800-066 | Canada | 1-800-663-7174 |
| China | 108-66 | Denmark | 800-100-66 |
| Finland | 9800-10660 | Germany | 0130-880-066 |
| Hawaii | 1-800-865-8424 | Hong Kong | 800-0066 |
| India | 000-66-17 | Indonesia | 001-801-66 |
| Israel | 177-660-2727 | Italy | 172-1066 |
| Japan | 003-9-661 | Korea (Telecom) | 009-66 |
| Korea (Dacom) | 0039-66 | Macau | 0800-660 |
| Netherlands | 060-220-166 | New Zealand | 000-966 |
| Norway | 800-19966 | Philippines (PLDT) | 00566 |
| Philippines (Philcom) | 102-666 | Portugal | 050-176610 |
| Singapore | 8000-660-660 | Spain | 9001-99-0066 |
| Taiwan | 008-066-0066 | United Kingdom (BTI) | 0800-89-0066 |
| United Kingdom (MCI) | 0500-89-0066 | USA (AT&T) | 1-800-342-0066 |
| USA (MCI) | 1-800-678-8424 | USA (Sprint) | 1-800-745-0660 |
| United Arab Emirates | 800-11-66 |
Home Direct allows visitors to Thailand an easy way to contact an operator in their own country. It is especially helpful for those who do not speak Thai and those making collect calls. Calls are charged at the destinations overseas operator rate.
| To | Dial | To | Dial |
| Australia (Telstra) | 001-999-61-1000 | Australia (Opus) | 001-999-61-2000 |
| Canada | 001-999-15-1000 | Denmark | 001-999-45-1000 |
| Finland | 001-999-358-1000 | Germany | 001-999-49-1000 |
| Hawaii | 001-999-14424 | Hong Kong | 001-999-852-1086 |
| Indonesia | 001-999-62-1000 | Israel | 001-999-972-1000 |
| Italy | 001-999-39-1000 | Japan | 001-999-81-1000 |
| Korea | 001-999-82-1000 | Macau | 001-999-853-1000 |
| Netherlands | 001-999-31-1035 | New Zealand | 001-999-64-1066 |
| Norway | 001-999-47-1000 | Philippines (PLDT) | 001-999-63-1000 |
| Philippines (Philcom) | 001-999-63-1000 | Portugal | 001-999-351-1000 |
| Singapore | 001-999-65-0000 | Spain | 001-999-34-1066 |
| Taiwan | 001-999-886-1000 | United Kingdom (BTI) | 001-999-44-1066 |
| United Kingdom (MCI) | 001-999-44-2000 | USA (AT&T) | 001-999-11111 |
| USA (MCI) | 001-999-12001 | USA (Sprint) | 001-999-13877 |
| United Arab Emirates | 001-999-971-1000 |