BBC, Deutsche Welle, and Radio Free Europe/Radio Liberty, Radio Free Asia, Sound of Hope etcetc actually setup special stations around the soviet bloc countries in an action that could viewed as equally clandestine as the jammers that were trying to silence them.
Given the connection with a one-time pad, I wonder why the article refers to the technique as "cryptology". Wouldn't "cryptography" be the correct term, given the security afforded by a one-time pad is unmatched?
https://www.rferl.org/a/mystery-numbers-station-persian-sign...