Civilian side radio users, like fire, ems, or police, have a different one

911 dispatcher here- pretty much everywhere around me uses the NATO phonetics, except one neighboring county that I'm pretty sure doesn't use any sort of standardized phonetics at all, or at least their officers and dispatchers and such can't be bothered to use it.

Things aren't totally standardized across the country though, different 10-codes (or no 10-codes at all,) different terminology, different phonetic alphabets, etc.

There's some old timers around my county who have been around forever who tend to fall back into other systems from time to time, or people occasionally have a brain fart and have to spit out something different on the spot.

I'm pretty sure APCO at least strongly recommends using the NATO alphabet.