If you want someone to be actually pedantic about it, then no system is ever classified. Knowledge of the system might be classified, the system may be accredited to handle classified data, at some level. The data this system allegedly collects is obviously unclassified and only becomes classified after landing in some data lake.

Information is classified not anything else. All of that to say, this is one of the many secret computer systems the nsa allegedly has. As the Wikipedia article clearly indicates