I just finished reading another article about counterfeit goods from China. Not just fashions, but sophisticated technical gear. Common sense should tell us that there is a black market for cell phone simulators that are sold to bad guys instead of government. It is hard to imagine how many of those things are hiding near FBI headquarters, the White House, NSA, and local law enforcement.
I'm sure that government could design phones immune to sniffing, but outside the military they probably don't. Given the FBI's record with handling email technology, I expect that a secure phone engineered for the FBI would weigh no less than 50 pounds. Government and law enforcement uses the same brands of phones as we do.
On a similar theme, I saw an article about a European device that alarms when it detects encrypted radio transmissions nearby of the kind used by their police. It could give warning of an impending raid.