Editing Numbers station (section)

== Suspected use for espionage ==

It has long been speculated, and was argued in one court case, that these stations operate as a simple and fool-proof method for government agencies to communicate with spies working undercover.<ref>{{cite book |last=Wagner |first=Thomas |year=2004 |title=If it had Not Been for Fifteen Minutes: A true account of espionage and hair-raising adventure |chapter=Chapter&nbsp;6 – So here she was, with a pillow over her head and over the radio&nbsp;... |chapter-url=http://radio-weblogs.com/0101986/stories/2002/04/24/ifItHadNotBeenFor15MinutesChapter6.html |access-date=30 October 2013}}</ref> According to this hypothesis, the messages must have been encrypted with a [[one-time pad]] to avoid any risk of decryption by the enemy. Writing in 2008, Wallace & [[H. Keith Melton|Melton]] described how numbers stations could be used in this way for espionage:<ref name="Wallace-Melton-2008">{{harvnb|Wallace|Melton|2008|p=438}}</ref>

:The [[one-way voice link]] (OWVL) described a covert communications system that transmitted messages to an agent's unmodified shortwave radio using the high-frequency shortwave bands between {{nobr|3 and 30 MHz}} at a predetermined time, date, and frequency contained in their communications plan.<ref name="Wallace-Melton-2008" />
: The transmissions were contained in a series of repeated random number sequences and could only be deciphered using the agent's one-time pad. If proper tradecraft was practised and instructions were precisely followed, an OWVL transmission was considered unbreakable. As long as the agent's cover could justify possessing a shortwave radio and he was not under technical surveillance, high-frequency OWVL was a secure and preferred system for the CIA during the Cold War.<ref name="Wallace-Melton-2008" />

Evidence to support this theory includes the fact that numbers stations have changed details of their broadcasts or produced special, nonscheduled broadcasts coincident with extraordinary political events, such as the [[1991 Soviet coup d'état attempt|attempted coup of August&nbsp;1991]] in the [[Soviet Union]].<ref>{{cite report |title=Irdial-Discs, included booklet |series=[[The Conet Project]] |website=hyperreal.org |page=59 |url=http://irdial.hyperreal.org/www/conet_project_booklet.pdf |archive-url=https://web.archive.org/web/20060425154733/http://irdial.hyperreal.org/www/conet_project_booklet.pdf |url-status=dead |archive-date=25 April 2006 }}</ref>

A 1998 article in ''[[The Daily Telegraph]]'' quoted a spokesperson for the [[Department of Trade and Industry (United Kingdom)|Department of Trade and Industry]] (the government department that, at that time, regulated radio broadcasting in the United Kingdom) as saying
: "These [numbers stations] are what you suppose they are. People shouldn't be mystified by them. They are not for, shall we say, public consumption."<ref name=Pescovitz1999>{{cite magazine |first=David |last=Pescovitz |date=16 September 1999 |title=Counting spies |magazine=Salon |url=http://www.salon.com/1999/09/16/numbers_2/ |url-status=live |access-date=12 March 2016 |archive-url=https://web.archive.org/web/20000119102137/http://salon.com/people/feature/1999/09/16/numbers/print.html |archive-date=19 January 2000 |df=dmy-all }}</ref>