Officers dispatched mainly by their local detachments, no Comm Centres. Also the detachment dispatchers could/would talk to one another over the air. No mobile repeaters let alone a portable radio.
Barrie was a regional comm centre that covered Orillia to Alliston and Bala / Port Carling
area as well if I recall correctly (forgive me if I'm wrong on this as it's going back some).
And I think it was Aurora that covered King, Caledon, Bolton etc. and I don't remember if they dispatched for Downsview or not as well.
I remember 458.8625 or 458.5625MHz. I could have told you for sure if I hadn't thrown out my PAC-RT that still had the crystals in it.