Prefixes that are used for radio and television are usually allocated by ITU. They also form the basis for, but do not exactly match, aircraft registration identifiers. But in some cases, especially among amateur radio operators other, by ITU unallocated, callsigns are used when operating from disputed areas or countries that are internationally not (yet) recognized. They can be:
- unofficial - used by individuals without any issued permit
- temporary - issued by local authority
- official - recognized internationally by different organisations
Prefixes for those stations are either unallocated or unavailable by ITU definitions.
Unallocated: The following call sign prefixes are available for future allocation by the ITU. (x represents any letter; n represents any digit from 2–9.)
- E8, E9, H5, J9, On, S4, T9*, Un, V9, Xn, YZ*, Z4–Z7, Z9, 4N*.
(* Indicates a prefix that has recently been returned to the ITU.)
Unavailable: Under present ITU guidelines the following call sign prefixes shall not be allocated . (x represents any letter; n represents any digit from 2–9.)
- 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 (nn) are not as yet considered by the ITU.
Table of Non-ITU radio prefixesEdit
|Call Sign Series||State / territory||Status||Organisation(s)|
|0Q||Bavaria||Official status unknown / unofficial||N/A|
|0S||Principality of Seborga||Official status unknown / unofficial||N/A|
|1A||Sovereign Military Order of Malta||Official, DXCC entity||SMOM Sovereign Military Order of Malta|
|1B||Northern Cyprus||Official status unknown / unofficial||N/A|
|1C||Chechnya||Unofficial - now RA6||N/A|
|1L||Liberland||Temporary||LARA Liberland Amateur Radio Association|
|1S||Spratly Islands||Unofficial - now 9M0, DX0 or BV9, DXCC entity||N/A|
|1SL, 1S||Principality of Sealand||Official status unknown / unofficial||N/A|
|1X||Chechnya||Unofficial - now RA6||N/A|
|1Z||Kayin State||Official status unknown / unofficial||N/A|
|D0–D1||Donetsk People's Republic||Official status unknown / unofficial||Unknown|
|H5||Bophuthatswana||Official status unknown / unofficial||N/A|
|M1||San Marino||Temporary, no longer used - now T7||N/A|
|S0||Western Sahara||Official, DXCC entity||Western Sahara's Amateur Radio Society (SØ1WS)|
|S4||Ciskei (South Africa)||Unofficial, no longer used - now ZS||N/A|
|S8||Transkei||Unofficial, no longer used - now ZS||N/A|
|T0||Principality of Seborga||Official status unknown / unofficial||N/A|
|T4||Venda (South Africa)||Unofficial, no longer used - now ZS
Prefix is assigned to Cuba
|T8||Principality of Seborga||Official status unknown / unofficial
Prefix is assigned to Palau
|V9||Vendaland (South Africa)||Unofficial, no longer used - now ZS||N/A|
|X5||Bosnia and Herzegovina||Temporary, no longer used - now E7||N/A|
|Z6||Kosovo||Official in Kosovo, unapproved by ITU 
DXCC entity 
|SHRAK Shoqata e Radioamatorëve të Kosovës|