ITU prefix
The International Telecommunication Union allocates call sign prefixes for radio and television stations of all types. They also form the basis for, but do not exactly match, aircraft registration identifiers. These prefixes are agreed upon internationally, and are a form of country code. A call sign can be any number of letters and numerals but each country must only use call signs that begin with the characters allocated for use in that country.
A few countries do not fully comply with these rules. Australian broadcast stations officially have—but do not use—the VL prefix, and Canada uses Chile's CB for its own Canadian Broadcasting Corporation stations. This is through a special agreement with the government of Chile, which is officially assigned the CB prefix.
With regard to the second and/or third letters in the prefixes in the list below, if the country in question is allocated all callsigns with A to Z in that position, then that country can also use call signs with the digits 0 to 9 in that position. For example, the United States is assigned KA-KZ, and therefore can also use prefixes like KW0 or K1.
Many large countries in turn have internal rules on how and where specific subsets of their callsigns can be used, which are not covered here.
Unallocated and unavailable call sign prefixes
Unallocated: The following call sign prefixes are available for future allocation by the ITU.- E8, E9, H5, J9, On, S4, T9*, Un, V9, Xn, YZ*, Z4-Z7, Z9, 4N*.
- nn, x0, x1, 0x, 1x, Qx.
- no prefixes beginning with Q are used—they may be confused with Q codes.
- no prefixes with the digits 1 or 0 are used—they may be confused with the letters I or O.
- two digit prefixes are not as yet considered by the ITU.
Allocation table
| Call Sign Series | Allocated to |
| AA-AL | United States |
| AM-AO | Spain |
| AP-AS | Pakistan |
| AT-AW | India |
| AX | Australia |
| AY-AZ | Argentina |
| A2 | Botswana |
| A3 | Tonga |
| A4 | Oman |
| A5 | Bhutan |
| A6 | United Arab Emirates |
| A7 | Qatar |
| A8 | Liberia |
| A9 | Bahrain |
| B | People's Republic of China |
| B | Taiwan |
| CA-CE | Chile |
| CF-CK | Canada |
| CL-CM | Cuba |
| CN | Morocco |
| CO | Cuba |
| CP | Bolivia |
| CQ-CU | Portugal |
| CV-CX | Uruguay |
| CY-CZ | Canada |
| C2 | Nauru |
| C3 | Andorra |
| C4 | Cyprus |
| C5 | The Gambia |
| C6 | The Bahamas |
| C7 | World Meteorological Organization |
| C8-C9 | Mozambique |
| DA-DR | Germany |
| DS-DT | South Korea |
| DU-DZ | Philippines |
| D2-D3 | Angola |
| D4 | Cape Verde |
| D5 | Liberia |
| D6 | Comoros |
| D7-D9 | South Korea |
| EA-EH | Spain |
| EI-EJ | Ireland |
| EK | Armenia |
| EL | Liberia |
| EM-EO | Ukraine |
| EP-EQ | Iran |
| ER | Moldova |
| ES | Estonia |
| ET | Ethiopia |
| EU-EW | Belarus |
| EX | Kyrgyzstan |
| EY | Tajikistan |
| EZ | Turkmenistan |
| E2 | Thailand |
| E3 | Eritrea |
| E4 | Palestinian Authority |
| E5 | Cook Islands |
| E6 | Niue |
| E7 | Bosnia and Herzegovina |
| F | France ' |
| G | United Kingdom ' |
| HA | Hungary |
| HB | Switzerland |
| HB | Liechtenstein |
| HC-HD | Ecuador |
| HE | Switzerland |
| HF | Poland |
| HG | Hungary |
| HH | Haiti |
| HI | Dominican Republic |
| HJ-HK | Colombia |
| HL | South Korea |
| HM | North Korea |
| HN | Iraq |
| HO-HP | Panama |
| HQ-HR | Honduras |
| HS | Thailand |
| HT | Nicaragua |
| HU | El Salvador |
| HV | Vatican City |
| HW-HY | France ' |
| HZ | Saudi Arabia |
| H2 | Cyprus |
| H3 | Panama |
| H4 | Solomon Islands |
| H6-H7 | Nicaragua |
| H8-H9 | Panama |
| I | Italy |
| JA-JS | Japan |
| JT-JV | Mongolia |
| JW-JX | Norway |
| JY | Jordan |
| JZ | Indonesia |
| J2 | Djibouti |
| J3 | Grenada |
| J4 | Greece |
| J5 | Guinea-Bissau |
| J6 | Saint Lucia |
| J7 | Dominica |
| J8 | Saint Vincent and the Grenadines |
| K | United States |
| LA-LN | Norway |
| LO-LW | Argentina |
| LX | Luxembourg |
| LY | Lithuania |
| LZ | Bulgaria |
| L2-L9 | Argentina |
| M | United Kingdom ' |
| N | United States |
| OA-OC | Peru |
| OD | Lebanon |
| OE | Austria |
| OF-OJ | Finland |
| OK-OL | Czechia |
| OM | Slovakia |
| ON-OT | Belgium |
| OU-OZ | Denmark |
| PA-PI | Netherlands |
| PJ | Netherlands – Former Netherlands Antilles |
| PK-PO | Indonesia |
| PP-PY | Brazil |
| PZ | Suriname |
| P2 | Papua New Guinea |
| P3 | Cyprus |
| P4 | Aruba |
| P5-P9 | North Korea |
| R | Russia |
| SA-SM | Sweden |
| SN-SR | Poland |
| SSA-SSM | Egypt |
| SSN-STZ | Sudan |
| SU | Egypt |
| SV-SZ | Greece |
| S2-S3 | Bangladesh |
| S5 | Slovenia |
| S6 | Singapore |
| S7 | Seychelles |
| S8 | South Africa |
| S9 | São Tomé and Príncipe |
| TA-TC | Turkey |
| TD | Guatemala |
| TE | Costa Rica |
| TF | Iceland |
| TG | Guatemala |
| TH | France ' |
| TI | Costa Rica |
| TJ | Cameroon |
| TK | France ' |
| TL | Central African Republic |
| TM | France ' |
| TN | Republic of the Congo |
| TO-TQ | France ' |
| TR | Gabon |
| TS | Tunisia |
| TT | Chad |
| TU | Ivory Coast |
| TV-TX | France ' |
| TY | Benin |
| TZ | Mali |
| T2 | Tuvalu |
| T3 | Kiribati |
| T4 | Cuba |
| T5 | Somalia |
| T6 | Afghanistan |
| T7 | San Marino |
| T8 | Palau |
| UA-UI | Russia |
| UJ-UM | Uzbekistan |
| UN-UQ | Kazakhstan |
| UR-UZ | Ukraine |
| VA-VG | Canada |
| VH-VN | Australia |
| VO | Canada |
| VP-VQ | United Kingdom ' |
| VR | Hong Kong |
| VS | United Kingdom |
| VT-VW | India |
| VX-VY | Canada |
| VZ | Australia |
| V2 | Antigua and Barbuda |
| V3 | Belize |
| V4 | Saint Kitts and Nevis |
| V5 | Namibia |
| V6 | Federated States of Micronesia |
| V7 | Marshall Islands |
| V8 | Brunei |
| W | United States |
| XA-XI | Mexico |
| XJ-XO | Canada |
| XP | Denmark |
| XQ-XR | Chile |
| XS | People's Republic of China |
| XT | Burkina Faso |
| XU | Cambodia |
| XV | Vietnam |
| XW | Laos |
| XX | Macao |
| XY-XZ | Burma |
| YA | Afghanistan |
| YB-YH | Indonesia |
| YI | Iraq |
| YJ | Vanuatu |
| YK | Syria |
| YL | Latvia |
| YM | Turkey |
| YN | Nicaragua |
| YO-YR | Romania |
| YS | El Salvador |
| YT-YU | Serbia |
| YV-YY | Venezuela |
| Y2-Y9 | Germany |
| ZA | Albania |
| ZB-ZJ | United Kingdom ' |
| ZK-ZM | New Zealand |
| ZN-ZO | United Kingdom ' |
| ZP | Paraguay |
| ZQ | United Kingdom ' |
| ZR-ZU | South Africa |
| ZV-ZZ | Brazil |
| Z2 | Zimbabwe |
| Z3 | North Macedonia |
| Z8 | South Sudan |
| 2 | United Kingdom ' |
| 3A | Monaco |
| 3B | Mauritius |
| 3C | Equatorial Guinea |
| 3DA-3DM | Swaziland |
| 3DN-3DZ | Fiji |
| 3E-3F | Panama |
| 3G | Chile |
| 3H-3U | People's Republic of China |
| 3V | Tunisia |
| 3W | Vietnam |
| 3X | Guinea |
| 3Y | Norway |
| 3Z | Poland |
| 4A-4C | Mexico |
| 4D-4I | Philippines |
| 4J-4K | Azerbaijan |
| 4L | Georgia |
| 4M | Venezuela |
| 4O | Montenegro |
| 4P-4S | Sri Lanka |
| 4T | Peru |
| 4U | United Nations |
| 4V | Haiti |
| 4W | Timor-Leste |
| 4X | Israel |
| 4Y | International Civil Aviation Organization |
| 4Z | Israel |
| 5A | Libya |
| 5B | Cyprus |
| 5C-5G | Morocco |
| 5H-5I | Tanzania |
| 5J-5K | Colombia |
| 5L-5M | Liberia |
| 5N-5O | Nigeria |
| 5P-5Q | Denmark |
| 5R-5S | Madagascar |
| 5T | Mauritania |
| 5U | Niger |
| 5V | Togo |
| 5W | Western Samoa |
| 5X | Uganda |
| 5Y-5Z | Kenya |
| 6A-6B | Egypt |
| 6C | Syria |
| 6D-6J | Mexico |
| 6K-6N | South Korea |
| 6O | Somalia |
| 6P-6S | Pakistan |
| 6T-6U | Sudan |
| 6V-6W | Senegal |
| 6X | Madagascar |
| 6Y | Jamaica |
| 6Z | Liberia |
| 7A-7I | Indonesia |
| 7J-7N | Japan |
| 7O | Yemen |
| 7P | Lesotho |
| 7Q | Malawi |
| 7R | Algeria |
| 7S | Sweden |
| 7T-7Y | Algeria |
| 7Z | Saudi Arabia |
| 8A-8I | Indonesia |
| 8J-8N | Japan |
| 8O | Botswana |
| 8P | Barbados |
| 8Q | Maldives |
| 8R | Guyana |
| 8S | Sweden |
| 8T-8Y | India |
| 8Z | Saudi Arabia |
| 9A | Croatia |
| 9B-9D | Iran |
| 9E-9F | Ethiopia |
| 9G | Ghana |
| 9H | Malta |
| 9I-9J | Zambia |
| 9K | Kuwait |
| 9L | Sierra Leone |
| 9M | Malaysia |
| 9N | Nepal |
| 9O-9T | Democratic Republic of the Congo |
| 9U | Burundi |
| 9V | Singapore |
| 9W | Malaysia |
| 9X | Rwanda |
| 9Y-9Z | Trinidad and Tobago |