North Korea supposedly still uses numbers stations to contact infiltrators. Though, they may just keep the stations as a way to ratchet up tensions with South Korea, given that numbers stations are a bit anachronistic. Who knows! It's interesting though.

https://en.yna.co.kr/view/AEN20200829002300315

https://world.kbs.co.kr/service/news_view.htm?lang=e&Seq_Cod...

They've done it before as well (better source + more detail, but less current):

https://www.nytimes.com/2016/07/22/world/asia/north-korea-sp...

https://en.wikipedia.org/wiki/Numbers_station