Tom,
The story I have been told is Shelby County didn't want to pay user fees to the state, so for around $12M they are standing up their own. And will be charging user fees to the users. And if the user decides not to use the system, the 911 center will not support them. And if a user is on the edge of the county, they will not allow other systems in thier radios nor allow their system in other radios, so they will need 2 radios (1 for Marcs and 1 for Shelby Co). Hows that for interoperability? All the counties around Shelby are on Marcs.
System is running in test mode currently.