Montreal is 6 hours behind Oslo
Best overlap: 2:00 PM to 6:00 PM in Oslo is 8:00 AM to 12:00 PM in Montreal.
For the smoothest call, aim inside 2:00 PM to 6:00 PM in Oslo, i.e. 8:00 AM to 12:00 PM in Montreal. Montreal is 6 hours behind Oslo, so you've got a workable 4-hour overlap — ideal for a standing meeting around 2:00 PM in Oslo (8:00 AM in Montreal).