HI, I don't know if this is your answer, but I used to work w/ 9-1-1/law enforcement, and I can tell you that most of the time, we would get calls about #'s like this it was telemarketers hiding the number they are calling from. can come up as all 9's or some other crazy numbers. just fyi, they can also pirate someone else's caller id and have that show up on your phone as well. It must be pretty easy to do, because I know of some high school students that have done it regularly when they prank people. I also, have gotten similar texts w/ the 9's and it was always unsolicitied sales of something or another. Hope that helps you out.
also, this could be a mass text sent from somewhere, like an auto dialer. A lot of telemarketers are using this sales technique and that could be what the other descending # is all about.