[TrunkCom] partial encryption and if so how is this possible?

[Jeff Kenyon]

Good morning to all on the list.  I have noticed that when listening to
conversations on Michigan.s digital 800 MHz system (MPSCS) there have been
times where conversations are partially encrypted.  This morning I heard
what sounded like some kind of road commission or something, but one side
of the conversation was clear and the other was encrypted.  I.ve never
known any system to do this, and the person who was clear wasn.t asking
the person who was encrypted for a retransmit or anything.  As I said I
only got to listen to this for a few minutes and couldn.t guess on what
the agency was, but I found this to be strange.