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 last digit) to be assigned. By October 1991, the numbering plan area (NPA) had been assigned to relieve exchanges in what was, then as now, Canada's largest toll-free calling zone. Automatic number identification (ANI) on the NPA's switching systems began transmission on October 11, 1992 for some central office codes, and full conversion was achieved by January 1, 1994.
Five years after its introduction, 905 was close to exhaustion far sooner than anticipated due to Canada's inefficient system of number allocation (with no number pooling in Canada, blocks of 10,000 numbers were assigned to each CLEC in each tiny hamlet served, with most of these wasted). This was exacerbated by the proliferation of cell phones, fax lines, and secondary phone lines for home dial-up Internet use. By 1999, the CRTC had established an ad-hoc committee to study NPA relief planning for area code 905. A split of the 905 NPA was considered, with various options presented:
a geographic split by municipality (either two-way or three-way)
a geographic split of concentric rings around Toronto
re-aligning NPA boundaries (some areas retain 905, others acquire a new NPA); that is, a municipality and exchange split
a distributed overlay
The overlay option was chosen because it would cause the least disruption; it would require no changes for existing customers in the 905 area. It would also be far easier to implement technically.
The 289 NPA overlay was approved by the CRTC on August 15, 2000 (Order CRTC 2000-772). Earlier that month, Toufic Saliba, consultant and technical engineer at the Commission, directed the addition of area code 289 in the 905 area code region. In doing so, Saliba directed that all carriers put in place a 10-digit dialing plan for all local calls. In this order, the Commission directed Bell Canada to implement the 10-digit local dialing plan. 289 came into service on April 7, 2001, and was in full operation by June 9, 2001.
905 officially became exhausted in November 2005. All new central office prefixes are assigned in NPA 289, as there are no longer any available prefixes in 905. Due to the fact that this is a large and rapidly growing region, area code 365 has been assigned for further relief on March 25, 2013, and area code 742 has been set aside for further relief as the area is expected to exhaust by 2036 at current growth rates.
In popular culture
The term the 905 or the 905 belt is used to describe the suburban areas of the Greater Toronto Area, while Toronto proper is referred to as the 416. The term 905er is often used pejoratively by downtown and inner-city Toronto residents to refer to people from Toronto's suburbs.
Canadian rapper Maestro rendered homage to the area code in his song "416/905 (TO Party Anthem)".
^"905 region to add new area code". CBC News. April 13, 2010. Retrieved April 18, 2010. "The area around Toronto is known colloquially as "the 905," after the area code that was added in 1993 and covers such areas as Mississauga and Niagara Falls."