DHS probably won't know.
Wyden of all people should probably know he needs to ask NSA if there are FISA warrants for anyone running IMSI catchers, and he knows full well that the response won't be public, if anything is said publicly they'll cite PL 86-36 which is an answer in and of itself that yes, they know who it is and why.
The United States is not the only country that produces them and I'd be willing to bet that they're either Chinese or Russian and being used to put together target lists. Task Force Orange does much the same thing in Beijing and Moscow.
Biting the hand that feeds IT
