Sure, the web sites are blocked, but radio waves couldn't be. And traditionally there were always enough radio stations carefully built and sufficiently financed to cover the target areas.

RFA:

https://www.rfa.org/about/info/frequencies.html

VOA:

https://translate.google.com/translate?sl=auto&tl=en&u=https...

A nice example of what one U.S. journalist knew regarding the coverage of North Korea in 2013:

https://www.northkoreatech.org/2013/04/11/us-wants-voa-rfa-t...