461.4625 was in use last year for school busses in Mississauga using NXDN. It's quiet right now.At least try 452.7375, 460.9875, 461.4625, 462.0375. Those are main ones used elsewhere. Maybe the Ottawa radios have those programmed as well.
452 and 460, 462 are definitely being used around Toronto on NFM. Waiting to see if 461.4625 is still in use.