An unfortunate side effect of the way HAM licenses are handled worldwide is that each government has a handy list of almost every citizen with enough knowledge and experience to build, service and use radio stations - complete with addresses and a partial inventory of equipment in circulation. It makes confiscating radio equipment and detaining operators much, much easier.
The knowledge is free and available to all and not that difficult. Amateur, citizens, and even AM/FM are cheap and easy to operate.
We are talking about how people get a message out in a martial law / wartime scenario. Radio is your best bet because no one can really stop you the way they can block and DNS server or just outright tell the ISP to shutdown.
Radio is difficult if not impossible to block with clever operators. The system is known.
Satellite will always be subject to whoever is in power at the time and it won't work within a building.
If you want to get information in and out the best option is—and possible always will be–a network of skilled radio operators.