Comment by jiveturkey

I was going to suggest LoRA.

But a country-sized network with the purpose of evading a blackout would likely have to be full mesh. A network organized into a hierarchy (aggregated routing tables) requires some coordination that could quickly be identified and squashed.

The size of such a mesh is limited by scaling factors, so this couldn't span a nation. Let's say you could do that though. The network would be completely choked up with traffic to the point of unusability.

I think starlink, satphone, maybe packet radio on small scale are the most realistic options.