As I understand it...
As I understand it, they have th conventional freqs to use during an emergency where they just want "on site" communications. Like maybe around the command post or the general area of a commend post in the event of some type of incident.
That way, they don't tie up important system time with "where's the bathroom go? or which tent has the food & coffee" types of traffic.
If you look at some of those conventional freqs, I think you'll see that they are common to just about every state that has a 800 system. Pretty much being set up to be able to use them "locally" on any event nationwide.
And, if every little agency that gets an 800 radio programs those freqs into their radios, the radios can be used by their personnel almost anywhere they might be requested to go, (At least on a "local" or on site basis after they get there...)
Steve/Gallia 911