Im in the Jefferson Co area and i have never heard a peep out of the TBI on these frequencies:
460.52500
460.55000
Any one else ever hear them on the scanner?
A peep is about all you'll hear. I have heard a security detail one time on 460.55 along with some P25 testing in P25 mode. That's about all I've heard.
The cell phone is probably their most widely used two way. Everyone rants and raves over stuff like Fedcom and stuff and there is stuff out there, what little isn't encrypted, but not too long ago when the DHS head (i can't pronounce her name, Janet something) came to Nashville the USSS was her detail. When they were on the move the report that they were on their way wasn't by radio but by the USSS agent at the aircraft answering his cell phone with the news. I was standing right beside him.
Yes, I have heard the two UHF channels from time-to-time, mostly stakeouts. They have a repeater network with different PL's to access different sites.