55xxx is the Prince George's County Units
0-2999 Dispatchers (Mostly Analog Talkgroups)
3000-4000 Calvert FD
5000-6000 Baltimore Co FD
11000-19999 Dispatchers (Digital)
21xxx-22xxx Fire Mobiles (These are the old vehicles mobiles)
24xxx Annapolis PD
25xxx Sheriffs, AACC
26xxx Detention, Aging, Buses
27xxx Schools, Buses
28xxx Parks
28xxx----29500 DPW
29501----31xxx Howard County
33xxx Baltimore City
36xxx Queen Annes
38xxx --39xxx Prince Georges
42xxx Crofton PD
42xxx Maryland State Police
43xxx BWI FD
44xxx---45xxx County Police
48xxx---49xxx County Fire
52xxx Reserve Communications Center, Dispatcher Training
55xxx Prince George's PD
61xxx Annapolis DPW,OEM, DOT
64xxx and above appear to be FiRST Radios (MSP, Kent County, MDTA)