I am surprised after reading some of the post that Wake doesn't do the same thing Mecklenburg does.
All out of county EMS/Rescue units contact CMED on either 340, 280, Ems Mutual Aid, or Mecklenburg Roamer Dispatch.
Ems Mutual Aid and Mecklenburg Roamer Dispatch are programmed into other 800 Mhz system users radios. (ie. Cabarrus, Rowan, York, etc).
Then they are patched to the hospital they are calling via patch across the Mecklenburg Hospital talkgroups.
As far as I know it works great in Mecklenburg, since they handle more than 20-25 out of county and South Carolina units making transports daily.
It is amazing how clear the reports are with the patch. I can have a VHF 340 radio and a scanner with the Mecklenburg 800 Mhz calling hospital programmed it and hear all transmission and the VHF scanner will not break squelch unless the unit is real close to my location.
Another interesting thing with Mecklenburg is. The way the system is set up is that there is a hospital 800 Mhz for all the hospitals in Mecklenburg County as well as a Hospital Talkgroup for all of the Hospitals outside of Mecklenburd that surround them.
Mecklenburg for the most part has a pretty good system to deal with out of county and South Carolina units that transport to Mecklenburg hospitals daily.
As far as I know Mecklenburg EMS Units don't even have VHF or UHF radios in the units anymore. They are strictly 800 Mhz Mobiles and Portables.
The only VHF Frequencies that are left are:
156.165 Mhz County Fire/Rescue Paging
154.280 Mhz State Fire Patch for use with out of county and state Mutual Aid
155.280 Mhz & 155.340 Mhz Used mainly for calling to request a patch to a Mecklenburg Hospital
Just my thoughts
David