Did a little research, MCA is owned by 4 companies with Huron Valley Ambulance being one of them. Looking in the MPSCS database under the EMS companies there is a category 'EMERGENT HEALTH PARTNERS TALK GROUPS'. It lists 2237 as a dispatch TG. The Monroe County DB lists HVA as having 4 UHF freqs for mobile extenders. I don't live down there so I can't help you with listening but hopefully this helps you.