Numbers stations have mostly spoken their otherworldly messages in obscurity. Save for a few intermittent news headlines and the 2013 John Cusack movie, "The Numbers Station," popular culture hasn't really attached many conspiracy theories to these strange transmissions.
In 1997, Irdial Discs released "The Conet Project," which was a four-CD compilation of numbers stations recordings, along with an extensive booklet that speculated about the purpose and origin of the broadcasts. At first the project found little media attention, but "Conet" now has a strong cult following amongst artists, conspiracy theorists, musicians and shortwave radio lovers.
"The Conet Project" arrived in the pre-Web days, long before search engines enabled casual surfers to research obscure topics with just a few keyboard strokes. Enough people were intrigued (or perhaps disturbed) by the things they heard on the CDs that at least one government agency was prompted to offer a statement, possibly to tamp down on further inquiries.
That statement came from a spokesperson from the United Kingdom, and it was appropriately vague. This statement said that the numbers stations are exactly what people think they are. "People shouldn't be mystified by them. They're not, shall we say, for public consumption" [source: Segal].
In the history of numbers stations, this is the nearest a government official has come to unveiling the exact purpose of the broadcasts. Considering that the stations are public knowledge and that hundreds or thousands of people must have worked in or around the transmissions, the stations continue to be obscured by an unusually ironclad secrecy.