Editing ITU prefix (section)

==Unallocated and unavailable call sign prefixes==
{{further|Non-ITU prefix}}
'''Unallocated:''' The following call sign prefixes are available for future allocation by the ITU. (''x'' represents any letter; ''n'' represents any digit from 2&ndash;9.)

* E8, E9, H5, J9, O''n'', S4, T9*, U''n'', V9, X''n'', YZ*, Z4&ndash;Z7, Z9, 4N*.

(* Indicates a prefix that has recently been returned to the ITU.)<ref group="Note">T9 is the former prefix of [[Bosnia and Herzegovina]]; it moved to E7 on 7 August 2007. YZ and 4N belonged to [[Yugoslavia]], along with 4O (which went to successor state [[Montenegro]]) and YT and YU (which went to successor state [[Serbia]]).<sup>{{Cite web |title=ITU Okays Montenegro, Serbia Call Sign Prefix Agreement |author=The ARRL Letter |url=https://www.eham.net/article/16670 |date=2007-05-17 |access-date=2023-05-05 |website=eHam.net}}</sup></ref>

'''Unavailable:''' Under present ITU guidelines the following call sign prefixes shall not be allocated.<ref>{{cite web|url=https://life.itu.int/radioclub/rr/res-13.pdf |title= RES13-1 RESOLUTION 13 (Rev.WRC-97) Formation of call signs and allocation of new international series |archive-url=https://web.archive.org/web/20221008043453/https://life.itu.int/radioclub/rr/res-13.pdf |archive-date=2022-10-08|work=Volume 3 - Resolutions and Recommendations – Edition of 2008
 |publisher=International Telecommunication Union|access-date=2023-05-04}}</ref> They are sometimes used unofficially – such as [[amateur radio]] operators operating in a disputed territory or in a nation state that has no official prefix (e.g. S0 in [[Western Sahara]] or station '''1A0''' at [[Sovereign Military Order of Malta|Knights of Malta]] headquarters in [[Rome]]). (''x'' represents any letter; ''n'' represents any digit from 2&ndash;9.)

* ''nn'', ''x''0, ''x''1, 0''x'', 1''x'', Q''x''.
* no prefixes beginning with '''Q''' are used—they may be confused with [[Q code]]s. Note that this applies to prefixes only - suffixes are the responsibility of the allocating country.
* 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.