Some notes I've gathered on ISSIs if anyone's interested. These can be useful to determine the purpose of newly discovered talk-groups by figuring out what users/radios have access
121XXXX replace XXXX with train car number
151XX seems to be allocated to group 115000
somewhere around 7000 to somewhere around 7500 are special constable radios seen on group 102740
40101 to 40115 Control on 101011 (Transit control)
5083 is Special Constable Control on group 102740 (Special Constables)
7600 is Wheel Trans Control user on group 101012 (Wheel Trans)
317227 is bus 7227, but i'm not sure if this will translate for all busses
some station collector handhelds, i would not trust these to remain the same as the portables will probably move from station to station from time to time
6761 Broadview
6765 College
6976 Finch
6762 Castle Frank
6616 Lawrence West
6816 Royal York
6763 Chester
6799 Main Street
6642 Saint Clair
6623 Victoria Park