I'm still unsure which ageny you are referring to.... I'll assume at this point it's OPP. ERT guys respond on whatever OPS channel they are assigned, which may get shifted over to a TAC channel at some point. You mentioned ERT, but I'm also wondering if you are referring to the TRU team. Again, they typically respond on whatever OPS or TAC channel has been assigned to the event, but will sometimes switch to their simplex encrypted channel when on scene (410.1875).