[matthewdgreen]

Googling “MTA Tetra” turns up a pile of articles about the deployment of TETRA trunked radio for communications in the NYC bus fleet and Staten Island Railroad. And in those articles there’s some controversy about the spectrum and interference issues. I don’t know where else they use TETRA, just that they were cited in some of the original articles about the vulnerabilities.

[crotchfire]

Ah, looks like they created a much lower-power TETRA in a different band for North American use (search for "low power tetra"):

https://www.powertrunk.com/pressroom/tetra-in-north-america/

That's cool, but it's going to be a niche use at those power levels. One of the things that make TETRA and P.25 so attractive is that you can put a huge, high-power repeater on a hill or tall building and cover a big chunk of a city using (fairly) small low-power handsets. Then multiple agencies (police, fire, spooks, clowns) can all use that repeater and share the cost burden.

The power-limited version looks like it'll always be a fairly niche single-agency-in-single-jurisdiction use. So the threat, while technically not zero, is not at the five-alarm-fire level that it is in Europe.

Edit: also looks like MTA bought their own spectrum license just for this one use:

   MTA owns licenses in 700 MHz and 800 MHz