Area code 365

Area codes 905, 289, and 365 are overlay area codes in the North American Numbering Plan (NANP) for southern Ontario, Canada. The plan area includes the Niagara Peninsula, Hamilton, Oshawa, and the suburban Greater Toronto Area. Area code 905 was assigned on October 4, 1993, as a split from area code 416. 289 was overlaid on June 9, 2001; since then, all local calls have required ten-digit dialling. On April 13, 2010, the Canadian Radio-television and Telecommunications Commission (CRTC) announced another overlay code for this area, 365. It became operational on March 25, 2013. A March 2013 report stated that the three area codes will exhaust by March 2025.

The plan area surrounds the overlay area of the city of Toronto, having area codes 416, 647, and 437. It is bound by area code 519 and 226 in the west, 705/249 in the north, 613/343 in the east, and New York State area code 716 on the eastern prong of the Niagara peninsula.

The incumbent local exchange carrier for these area codes is Bell Canada, which acquired the remaining independent company ca. 1980.

The 905 area code was once used as a block of alternate numbers for calls from the United States to Mexico (+52-5-...) in the days when overseas calls otherwise would have needed to be placed through a telephone operator. This use became obsolete with the widespread introduction of direct dial overseas calls and was completely abolished no later than February 1, 1991. Partly because of this prior usage of the number 905, area code 905 was the last of the "original-1947-format" area codes (that is, area codes with "0" [zero] or "1" [one] for the middle digit, and 2-9 for the first digit) to be assigned.

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