As an example, in my current home town of Cincinnati (I lived in Sacramento for 30 years before moving here 10 years ago) the City of Cincinnati and Hamilton County had a stand-alone P25 radio system consisting of two sites, one for the county and one for the city. Most, but not all, of the talk groups would roam between both sites providing radio coverage within the entire county.
Back then Butler County to the north was on a stand-alone P25 system, Warren County to the northeast was on a stand-alone analog system and Clermont County to the east was on a stand-alone analog system.
When Ohio MARCS started the Local Partnership Program Butler County connected its P25 controller to the MARCS core as a tier 5 partner and became the MARCS Zone 4 controller. Butler County doesn't pay subscriber fees because they maintain the county owned infrastructure themselves and allow other MARCS subscribers to roam to the site.
As time went on Warren County upgraded to P25 and connected its site to MACRS as a tier 4 partner. Warren County doesn't pay subscriber fees because they maintain the county owned infrastructure themselves and allow other MARCS subscribers to roam to the site.
Hamilton County and Cincinnati separately became tier 4 partners and connected both sites to the "Butler County" zone 4 controller. Both Hamilton County and Cincinnati don't pay subscriber fees because they maintain the county/city owned infrastructure themselves and allow other MARCS subscribers to roam to the sites.
Clermont County upgraded to P25 and became a tier 2 partner. Because the county paid for the upgrades to the infrastructure and then handed it over to MARCS they received a credit that was applied towards subscriber fees, when the credit runs out they will then begin paying subscriber fees.
Several of the other counties in the region are tier 1 partners and they pay subscriber fees and use sites installed and maintained by MARCS.
