Is there a low-bandwidth technology (probably some sort of radio) which allows communicating bits between two arbitrary points of the planet , in a practical way?<p>Satellite phones support voice and data, but I'm asking about something much simpler, just to be able to send a few bits now and then (eg. "I'm alive", or location).<p>Unfamiliar with Ham radio, I have the impression that it always requires experimenting and tinkerering, and not intended, in most of its forms, to be an invisible transport layer. I wonder if/why not there is a reliable global transport layer which can be used anywhere, even if at the price of having very low bit rates with high latency.