I should add that whatever I'm doing wrong here, none of these messages - iOS users, Android users, doesn't matter - are showing on the far side as having not been sent. They just silently, to both parties, don't arrive.
My sincere apologies to anyone who's tried to contact me in the last 24 hours. I'm not ignoring you. But as far as I can tell if I don't send you a text first everything I try to do trips over an edge case and falls into the void.