I have scoured the internet and no one seems to know, and I even called tech support. Some people say this might mean my number has been blocked, which is possible but I would not think likely.
I texted this person and got the error message immediately. I text another person afterwards to see if it was the same across the board but that person got my text just fine. As far as I know it is only this number.
Can you call the number and do they answer? Does it go to VM? If no to both, my guess you are blocked
Was reading it seems to be a Sprint error. Does this person use Sprint