Fort Erie, ON
reply to corster
Re: GTA getting new area codes 437 and 365 They were going to split 905 three ways when they did the original 289 overlay. One code for Hamilton/Niagara, one code for Halton/Peel and another for York/Durham. Problem was that they ran out of time for implementation and were forced into the overlay as a last-minute thing.
But yeah, they won't overlay any more. The costs associated with it are far greater. Most people wouldn't notice, but when you're reprinting all of your business cards, stationary and whatever else it can get expensive when you're doing a split every 5-15 years, with long and protracted fights over who gets to keep the area code. For areas that already do ten digit dialing there's nothing new to learn and an additional code makes the most sense.
As for what codes get selected, CNAC pre-assigns codes long before they're actually implemented. 905/289/365's fourth area code has already been assigned - 742. They also pre-assigned Toronto's fourth code but I can't remember what it is. For some reason I want to say it starts with 9. Both will be needed in about 15 years or so. All other Canadian area codes already have their relief codes pre-assigned, too.