St Paul has a battalion wide (6 site, growing to 7) repeater system using Fire 3 as the input to facilitate communications while responding to an incident. Scene communications are still direct using Fire 3 simplex. A common problem was enroute apparatus could not hear on-scene portables. As a side effect, they can also hear when another agency is talking to the dispatcher, so they do not attempt to contact them at the same time.
Hope that clears that up...
tpg