I've been arguing with a friend recently about The Imperium of Man and whether or not the internet or something resembling an internet exists in the 41st millenium. I say that it's there, even if unspoken, because there is no way the imperium would ever win any engagement ever with communications tech lower than 21st century standards. My friend says they all just use radio waves to communicate.

Who's right here? And no, I don't think they'd be using Astropathic Choirs to pinpoint where an earthshaker round needs to land, that would be a gross misuse of resources and/or reckless endangerment, in case a daemon popped out of the choirs heads.