MPSCS: St. Clair County (MI) Unknown Talkgroups
From The RadioReference Wiki
1443 - Possible national resource group
1973 - Herd testing and it being called channel 3
1978 - Herd testing and it being called channel 4 (same RID and voice as on 1973)
1979 - Same rid and voice as the other 2 groups
2681
2689
2759
2847
2861
2862
2912
11161
11718
11783
12007
12026
12156
12165
12166
12196
12248
12259
12529
12530
12535
12623
12866
12937
12940 - Possible US Customs
12951
22392