All the hospitals in Augusta use the H.E.A.R. channel for comms with the ambulance services, they have different frequencies allocated for comms within the hospital itself. Gold Cross E.M.S. has two different repeater frequencies assigned to them for dispatching in Richmond and Columbia Counties. The frequencies for the H.E.A.R. and Gold Cross can be found in the R.R. database. I'm unaware of any frequencies allocated to South Star ambulance or Capital City ambulance, Capital City does use Nextel for dispatching to their crews in Augusta.
The Gold Cross repeater on 154.2125mhz is simulcasted on the Palmetto 800 TRS. One of the crew members carries a VHF portable and another member carries an 800mhz portable. The 800mhz portable is used to contact FD first responders on the scene of an EMS call. Listen to the VHF side so you can hear both sides of their dispatches, the only time you'll hear both sides of the conversation on 800mhz will be when they use their 800mhz portable.
The repeater on 154.0025mhz is used for dispatching Gold Cross units in Columbia County as well as the Air Med helicopter. The repeater on 154.2125mhz is used for dispatching Gold Cross units in Richmond County, if you want to hear both sides of any conversation always listen to the VHF frequencies. I'm not aware of any tower purchases in Jefferson County but that would make sense because I heard that Gold Cross has, or will have, the contract there but can't confirm that. It'll make for good frequency fishing if they do get another frequency to use for Jefferson County.
I've heard the helicopter talking to dispatch as far away as Milledgeville, GA. I'm not sure how far they can talk to dispatch or, what their protocol is if they need to contact dispatch when on an out of town mission. They do give their GPS coordinates over the radio so one may be able to track them when they fly.