Comment by ac29

Trivial with the correct infrastructure - you can easily get 8kbps in 12.5kHz of bandwidth (a reasonably common channel size in the sub-GHz bands).

Trick is, you ideally need line of site (in which case your effective range is effectively the horizon), and directional antennas for distances more than a relatively short distance (a few miles maybe).

Some math follows. 30dBm is 1 W, and -100dBm is a low, but probably workable signal. We'll assume 0 antenna gain or loss to make the math easier.

Free Space Path Loss (in dB): 20×log10(d) + 20×log10(f) + 92.45

d=distance in km, f=frequency in GHz

So at 915MHz, we can get about 85km in free space @ 915MHz (this is actually past the horizon, so not really possible except from high elevations).

30dBm − (20×log10(85) + 20×log10(.915) +92.45) = -100dBm