Tell Toronto-area residents you live "in the 905" or "in the 416," and chances are they know what you're talking about.
But as of March 25, things get slightly more complicated.
As has happened elsewhere in Canada, the era of mass cellphones has left the designated-number system full to overflowing, and soon there won't be any more 416s or 905s to assign.
Help, however, is on the way, in the shape of additional new area codes that will allow up to seven million new numbers to be created.
In Toronto, the 416 and 647 area codes will be augmented by a new prefix: 437.
And within the mostly suburban domain of 905 and 289, the new three-digit face on the block will be 365.
Similar area-code additions have recently taken effect in northern Ontario, Quebec and Manitoba.
The changes were announced Wednesday by the Telecommunications Alliance, a network of service providers.
With the approval of the Canadian Radio-Television and Telecommunications Commission, they will be implemented late next month.
Similar expansions have been under way in other parts of Canada for several months.
In Québec, the new 873 area code was added to the 819 region in September.
In Manitoba, effective November, a new 431 area code was established alongside 204.
Other earlier additions included: 249 in the 705 area in northern Ontario; 579 in the 450 area in Québec; 343 in the 613 area in Ontario; 581 in the 418 area in Québec; 438 in the 514 area in Montreal; 587 in the 403 and 780 areas in Alberta; 226 in the 519 area in Ontario; and 778 in the 604 and 250 areas of British Columbia.