FleetNet Zone 3 covers (approximately) northeastern Parry Sound District, Nipissing District, Timiskaming District, Sudbury District, City of Greater Sudbury, Algoma District & Cochrane District (excluding Mooseonee and the James Bay coast which is not on FleetNet). In other terms, the Highway 11 corridor from south of North Bay north and west through Hearst as well as the Highway 17 corridor from about Bissett Creek (east of Mattawa) west through White River.
FleetNet Zone 4 covers (approximately) southern Kenora District (northern limits are around Balmerton on Highway 105 and Pickle Lake / Central Patricia on Highway 599), Thunder Bay District & Rainy River District. Otherwise the Highway 11 corridor from east of Longlac west to Rainy River along with the Highway 17 corridor from east of Marathon west to the Manitoba border. Coverage in both zones does not reach the far northern portions of the province.
There is very little in the database for Zone 4 due to its recent implementation and the smaller number of scannists than in the southern part of the province, so please search the system and submit what you find for frequencies and talkgroups to RR.
There were originally supposed to be 5 zones; however, for some reason this was reworked into the current 4. Zones 1, 2 & 3 are fully transitioned. Zone 4 is underway with MOH fully switched and OPP underway. I'm not sure about the other agencies in Zone 4.