By "each Medics" area of operation I assume you are referring to atlantic medics.
Atlantic MICU coverage areas, but not limited to. (keep in mind the MDT system will locate all units by GPS and generaly the closest unit goes and also that not all units are up 24/7)
Medic 1-westfield, mountainside, union, kenilworth
Medic 2-springfield, summit, milburn
Medic 3- Chatham, new providence, madison, berkley heights
Medic 6-East Hanover, livingston, florham park
Medic 7-montclair, bloomfield, cedar grove, verona, glen ridge,
Medic 8-Caldwell, north caldwell, west caldwell, fairfield
MIC 11- Morristown, Morris plains
MIC 12- Liberty corner, bernardsville, bedminster
Monoc 254 has the same coverage as Medic 6 and West Orange
When 7 or 8 gets dispatched 6 "floats" over to their coverage area
All of these dispatches can be heard on 155.355 Mhz(if you are close to the MICU you can usually hear their transmissions as well.) I have never heard 254 dispatches I figure they stick to the CAD system. I hope this helps you out!